Lewis is joined by two student co-hosts, Kavi Shama and Matt Turton, to discuss what Materials Science is with this month’s expert, Dr Kathy Christofidou.
Kavi (https://www.linkedin.com/in/ksharma96/) is a final year PhD student with the AMSCDT and is researching the cladding behaviour of high enrichment and high burn-up nuclear fuel: determining the impact of radiation damage on storage and corrosion. Kavi admits he is not the biggest cake fan, and instead would rather reach for a KitKat Chunky.
Matt (https://www.linkedin.com/in/matt-turton-4936a0202/) is a second-year PhD student, he graduated from the University of Sheffield with an MEng in Materials Science and Engineering in 2022. Matt is currently investigating the local structure of high entropy alloy with the aim of linking this to any properties of interest for nuclear fusion first shield wall applications. In his spare time, Matt enjoys playing rugby and going climbing, and says a Jam Roly-Poly is his favourite cake.
They’re both members of Lewis and Kathy’s research group; Modern AlChEME (see link below).
Kathy (https://www.linkedin.com/in/katerina-christofidou/) is a Senior Lecturer in Metallurgy at the University of Sheffield, Technology Platform Lead for the Henry Royce Institute in Materials Discovery and Prototyping, co-leads the Modern AlChEME research group, and is Admissions Tutor. In lieu of a more traditional cake, Kathy’s favourite dessert is Profiteroles.
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We really hope you’re enjoying Materials Unlocked and hope you can join us over on Instagram (https://www.instagram.com/materialsunlocked/) to see more resources from our various topics.
To find out more about the various organisations that have supported the production of this podcast please feel free to browse the links below:
• The Henry Royce Institute (http://www.royce.ac.uk) ; the UK’s national institute for advanced materials research and innovation
• Royce at the University of Sheffield (http://www.sheffield.ac.uk/royce-institute)
• The University of Sheffield (http://www.sheffield.ac.uk)
• EPSRC and SFI Advanced Metallic Systems Centre for Doctoral Training (http://www.sheffield.ac.uk/metallicscdt)
• Department of Materials Science and Engineering (https://www.sheffield.ac.uk/materials)
• Modern AlChEME (https://sites.google.com/sheffield.ac.uk/modernalchemegroup) research group
Hello and welcome to materials unlocked the podcast where we take a look at the less known subject of Material Science and try to unlock its Mysteries my name is Dr Lis Owen and I’m a lecturer at the University of Sheffield in each episode with the help of some students friends and colleagues
We’re going to delve into a particular topic and hopefully unlock its potential so this week we’re going to be talking about the materials design cycle and hopefully an overview of Material Science and what material science is and how it affects and shapes the world around us as always on every episode I’m
Going to be joined by a couple of our current students and this week it’s my very great pleasure to introduce K sha and Matt tarton KY and Matt welcome to the podcast hello hello so uh let’s just uh introduce yourselves a bit so cavy first time ever being on a podcast so
It’s going to be quite interesting like you said um one of your final year PhD students doing Material Science on nuclear materials which is pretty interesting yeah and Matt how about you what are you studying at the moment well I’m a second year PhD student and I’m investigating the local structure of H
Paro again for nuclear applications okay so quite so a high entropy alloy is probably something people haven’t heard of before so it’s probably quite a quite a complicated thing to be getting into very early in the podcast but that’s all right we we we can talk about it but
It’s a it’s a relatively new class materials that lots of Industry are quite interested in so maybe we’ll we’ll come back to that in a bit more detail later uh in the episode so both of you are currently doing phds in Material Science and as we said you’re both
Supervised by me you have the great pleasure of being supervised by me but were you both material scientists before doing a PhD I think Matt you yes been Material Science all the way through haven’t you yeah I’ve been Material Science did four years here at the
University of Sheffield m so why did you choose Material Science when you came to University uh well originally I wanted to do chemical engineering and then I saw at Manchester open day the store for Material Science you saw the light and and realized that that was the part
Of the engineering that I wanted to do I think that’s it’s it’s not so uncommon I mean I was a chemist as an undergraduate and have now moved into Material Science made that sort of slow transition over into Material Science but of now up there cavy what about you it seems I’ve
Lived Al turn to the life of Matt I was a I was a chemical engineer at Sheffield and then I took a year out to work in battery science right and then I came back to Sheffield to do Material Science PhD okay and now in in metals rather
Than in in in battery materials defitely so slightly different the battery science did not go well with it it was very slow paced and very monotonous y wasn’t your particular Cy no well we’re going to be talking about sort of Material Science in general and have a a
General overview so uh we’ll hopefully explore some of your experiences in the subject so far and talk a bit more about um why you got into the subject and your particular interests but we’re joined as well by a specialist Dr Kathy Christopher Kathy welcome to the podcast
Thank you so much it’s so great to be here now Kathy we have met before is that right just a little bit just a little tiny bit so for the listeners at home Kathy and I we did our phds together so we’ve known each other for
Quite a few years we won’t say how many so yeah many many years and now we run an academic group together we do indeed yes we run a group together called the modern Alchemy group that both Matt and cavy are part of and our sort of ethos
For the group is that we put materials design and characterization at the very center of it y so where I thought we’d start Kathy is um in your many hats and rolls and things that you have in the University one of them that you have is your the emissions tutor for the
Department and you and I have both been on open days talking to people like Matt trying to to to sell Material Science and explain to them why chemical engineering is not the way for them to go and that they should come and do materials instead when we talk to to people you
Know who are coming to the end of their school career and thinking about University and things there’s a lot of I think misunderstanding about what material science is and what it involves so I wondered if you could you could tell us a bit about your sort of experience talking to people about
Material Science and what they think it is and things like that yeah for sure it’s a really difficult one to explain to people to to be fair like as a first starter for 10 a lot of people we think that we’re talking about textiles for example or a particular class of
Materials and don’t really understand that there’s a lot more to materials in fact materials is everything from the chairs the Fabrics that our chairs are made out of to the uh the table and how it’s uh constructed to the airplanes that we fly on and the nuclear materials
That mat and cavy have been talking about as well everything is made out of materials and to make things better we need better materials so you can think back to I don’t know the R Brothers plane that was made out of wood and some canvas the principles haven’t changed at
All from that and suddenly we’ve got I don’t know the B52 bombers or things like that that are completely stealth and undetectable or of that is down to materials the fundamentals of how that works haven’t changed at all what’s changed is what we can do with materials
And how we can make things better yeah so I suppose one of the things that we sort of we take for granted is that we’ve we’ve always had just like stuff to make things out of like you know for years and years we’ve had Steels and you
Know bricks concrete or all of these things and we’ve always had sort of as I say just stuff lying around that we can manufacture something out of make something for a particular application or whatever but particularly I suppose now with those very high-end applications we now need to think in
Great depth about you know exactly what’s going into them and how we can make things for a particular like purpose and things but 100% I mean if we think about it historically we even name our historical eras after materials there’s the Stone Age the Bronze Age the
Iron Age everything is defined by how we actually figured out how to use materials in different ways um we’re now live in the Silicon age I don’t know what’s going to be next yeah and I think that’s the really exting thing about our sector in general what we can do to make
Materials and realize technologies that never existed before do you always find when you’re talking to you know friends and family and explaining what you do that you find it quite difficult to explain to them what what material science is and there’s a lot of sort of misconceptions about sort of materials
It is the most difficult thing to explain to people that don’t know what it is yeah I find it more difficult than talking about my research just to explain what material science is I tried to explain it to my dad this weekend and I just kept repeating the word Material
Science over again trying trying to get to trying to click and how to explain it in a simple way that people understand but it’s very very difficult so the thing when when you say something like with your research if you say something like nuclear or something people get a
Very clear image in in their mind as to as to what that is but with Material Science there’s just sort of nothing there people don’t necessarily have a touch as Kathy says you know it tends to be textiles or something they’re like oh fabric you know cotton wool things like
That but but it’s so much more it’s so much so much more than that so thinking then about materials design Kathy which you you sort of referenced and things so as I said for years we’ve just had had stuff around that we can we can make
Things out of but how do we then sort of go about developing a new material how do you go about like discovering something cuz when people talk about like you know thinking about s a different field obviously but think about like you know Mary cury discovering you know radium and things
Like that how how you go about designing a new material I think it’s just very alien to a lot of people and it’s something that they probably never considered about how we would go about that investigation and studies it’s absolutely true yeah we sort of tend to
Always start with what we have around us right so if you think about an application I don’t know let’s think about the nuclear reactors that Cav and Matt are working on the first instinct is what materials might be suitable that currently exist so we usually tend to
Start with something that we know and understand and is widely available the next step is we put it into service in the application and realize oh my God that was a terrible decision and we probably need to think about it in a little bit more detail so we start
Understanding how our technology and our application develops and how the material behaves in that application so from that point we start defining what properties our material will have to have so for example does it have to operate at really high temperatures that’s a key factor not all materials can do that
Does it have to be resistant to say water or radiation in that the case of the nuclear reactors so we start bringing all of that together and suddenly you don’t have a material that meets all of those conditions so we have to go back to the drawing board and
Understand how we can change a material or start completely from scratch to see how we can make something that meets all of those requirements or where it is that we can compromise on those requirements um so it is quite alien and the way that we do it and that’s the way
That we still do it we start with something that we know and we figure out that is not fit for purpose and then we start the design process from how is it not fit for purpose and how we can make a material better to uh be able to apply
It to that particular um service condition yeah and there’s that sort of gradual you talk about properties and sort of thinking about the different properties that are requ required for a for a different purpose and things and often when we’re when we’re then making the materials there’s a sort of
Balancing act to be done between the different properties that’s right yeah we need to balance a lot of things for example if you think about Metals a lot of the time we want to use a metal because it operates at fairly high temperatures but as it operates at high
Temperatures it might get soft it’s one of the only materials that can operate at high temperatures but it will get softer and softer and softer the more we use it so we might want to figure out how we can make it harder at those high temperatures so that it can retain its
Sort of rigidity so we we need to consider what are our compromise points and how we can then tackle those compromise points going forward so there’s a a related field I guess to materials design that is materials lifing where we effectively use a lot of statistics and a lot of the the physics
Based models that we have to understand how long a material will last in that specific application and usually we life it based on its weaker property effectively and that’s a key factor that we use particularly in areas where material failure might cause loss of human life like the nuclear industry
Like the Aerospace industry I think there’s like a also a misconception with how complicated it is to create a an alloy because some people think oh this material is hard this material is soft so if you mix them together it’ll make something in between and then that’ll be
Okay and that’s not always the case you can’t just never is it never is the case think are never as well behaved as we’d like there’s always a secondary re action or secondary phase or something that occurs within the combining of two things that you think should work
Together and it never makes sense yeah Nature has other ideas yeah so I think there’s a misconception of where it’s easy just to mix things together it just never works that way so in terms then of thinking if we if we’re thinking right from the beginning okay so you you said
That we’re going to approach a problem and think about what the application is so we we choose a particular application that we might want to to focus on and then we have to go about working out what properties are required for that particular application so I assume we
Therefore have to work very closely with engineers and you know people people in the sector to understand those S of responsibilities and things that’s right yes and that’s one of the really really fascinating things about Material Science because yes we understand our materials incredibly well but actually
We need to be the best multitaskers of the engineers because we need to be able to understand the nuclear engineers and we need to be able to understand the aerospace engineers and we need to be able to understand the chemical engineers and everybody’s design principles because often when you say
Design most people think about oh what are the stresses that this component is going to experience or um some other critical properties for example how much electricity do I need to get out of this particular component so we need to be able to understand all the different
Areas so that we can understand their requirements and then design our materials to adhere to those requirements which actually I mean you know I tend to think of Material Science as quite a sort of it it sits on those boundaries between a lot of fields and actually it’s it’s very
Interdisciplinary in nature and actually having different backgrounds like coming from chemical engineering and things like that sometimes gives you a slightly different sort of uh view of of a particular project or slight different understanding which is one of the reasons I find it find it quite exciting and interesting Kathy your background
Was Aerospace materials is that right that’s right remember that correctly um so yes you you came through materials sort of all all the way through I did yeah I came through um a material science and engineering department and I did a little bit of a a double major
Almost in some cases because we were doing a lot of the fundamentals of aerospace engineering things like structures and fluids and all of that and aerodynamics but that understanding of what is required then for the property so you can then sort of you know have that understanding yeah
Exactly yeah and then from there we build on the materials sort of side of things so the first couple of years we’re materials General engineering and then we moved on to a little bit more understanding on the Aerospace site so yeah it’s always important to have that
Sort of practical um practical focus in the mindset So Okay so we’ve got our we we’ve got our sort of design criteria I suppose and so we thought about um you know what application we’re doing and maybe selected some particular properties what’s the s next thing we
Might might do having sort of defined the problem that’s my favorite step it’s how we translate those properties to what we call micr structure MH so micro structure is what defines the properties of a material basically the smallest components that make up our material are basically what are going to govern our
Properties on the macro scale right so we build materials an atom at a time quite literally and how those atoms assemble themselves on the Nano and microscale is what allows us to tailor the properties in different ways so I can put maybe 10 atoms of chromium for
Example in steel and suddenly it becomes a stainless steel right so those little sort of architectural structures one atom at a time build up our micr structure and the micr structure is what allows us to get our compromise of the different properties so we can make material stronger we can make it more
Ductile we can make it harder more rigid whatever it is that we needed to do whether we wanted to conduct more electricity or not in some cases or whether we wanted to be um very resistant to high temperatures for example and I I think this is one of the
Things that coming from a chemistry background I hadn’t fully appreciated in Material Science was this importance of this thing that that that you call micros structure and actually understanding at every length scale the the the material so often people at school would have studied you know uh
Structures and thought about it in terms of solids liquids gases atoms you know they’ll have seen chemical formula possibly for you know a particular chemical structure of a material something like salt or something like that but that that sort of level that we’re talking about is is really really
Small it’s it’s sort of a 10 billionth of a meter in sort of length so if you were to line up 10 billion atoms um they would form the length of a a meter but going then up to the the next level in sort of length scale is something that I
Think a lot of people haven’t really thought about that sort of the the micro structure so here we’re talking sort of on the the the millionth of the meter scale right so we’re talking about like one in a million so if we were to line up a million objects along a meter rule
And often I I I I don’t know how you think about this but I sometimes think of it in terms of like Lego blocks or something like that and things sort of fitting together and right yeah that’s a really good analogy the different structures then affecting different
Properties and if you were to have like different shapes of Lego blocks it will give it sort of different strength and or how much space you have between the blocks and how how do you go about logically choosing what to start in obviously that originally it’ll be a lot
Of trial and error to get into find out what you need to do but obviously now now narrow age well how do you go with a logical step to do which material to put in or how to change the micr structure to get what you want that’s a really
Good question thanks c yeah so there are a lot of rules that we know empirically for example if we want the material to be very Ducar we know that if we make the atoms arrange in a very particular crystal structure in this Lego blogs for example we know what Lego block
Arrangement will be most helpful in keeping the ductility it doesn’t mean that that’s the best one but is a good way of starting out and sort of examining where we can go from there in addition to that we have a huge amount of modeling techniques that we can use
Now uh we’ve learned over the years and we started investigating the physics because at the end of the day it does come down to physics and how the the atoms arrang with each other so we can start using physics-based models to help guide our understanding of it for
Example this idea of adding chromium to iron that has been around empirically for years and years and years they never really understood how that helped until we got into electron microscopes and we discovered how we can actually examine the material down at the micr structure level it kind of worked and it was
Really good that it worked and it was kind of serendipitous that it worked but we didn’t understand why it worked until fairly recently realistically so now that we have that understanding we can start building on it with different models that we can then accelerate the way that we can make those decisions on
What the micr structure should look like and there’s a lot to learn still and those models that that that we’re using as you say they’re sort of I mean there are lots of different models out there some are more physics based some are more based on sort of just observing
Results and using things like machine learning in order to help interpret it and understand what’s going on but very often we then have to sort of you know repeat this process over and over again we use our model in order to create a material but then we need to test how
Good that model is because at the end of the day it’s only a model right we we have no idea if it’s if it’s going to give the right answer and so we then have to push the material through and test what’s going on which I think is
Then sort of the next stage that we go through in in the materials design process is actually you know making the material and and and see what’s going on yeah absolutely we can run all the models that we want but until we actually make and test something we
Won’t know what the answer is um so there’s a lot of experimentation that goes on and as you say machine learning is starting to help us to accelerate those processes and run those models a lot faster and artificial intelligence is coming in but at no point will they
Ever sort of take over from experimentation alone they might help us reduce the number of experiments that we want to do uh but we need to make materials and we need to test materials and it’s a great way of also getting an understanding of the manufacturing of
The material as well because we can make materials and we can have an idea of how we want the chemistry to look like but actually how we make something and how easy it is to make it is very very critical to whether that material will be successful I think Matt probably has
Some really good insights on making some materials that are very difficult to make yeah some of these materials that I’ve been making are quite hard to make going through Arc melting and then trying to balance the amount that you want to get out in the end with some of
Them volatilizing and just flying off elsewhere in the machine it’s a hard balance yeah so so when we’re when we’re making one of these test materials so let’s say we’ve we’ve gone through our our our we’ve we’ve spoken to to the engineers at whatever company we’ve chosen our properties and then we’ve
Done some models and we’ve predicted a particular composition that we might want to experiment with and then you’re melting it up so what sort of how how big is this this sample that we’re making up in terms of you know mass or size or just to give people an idea well
At at the moment I’ve been doing about 100 150 gr samples so quite small yeah and then when you want to bul that out to actual production stuff it’s going to change the micr structure and everything even more so you got one challenge in producing it in the small and then you
Got another challenge when you want to bulock it out we we’re starting with small pieces and then as you say scaling up but that scale up comes with it’s it its own set of problems associated with it you uh you mentioned something Arc melting uh can you just tell us a bit
About exactly what Arc melting is and you know how it works well it basically it uses um an arc produced from electrical current so about 200 400 amps is typically a good range of what I use and it produces a high temperature beam that you kind of direct at all of your
Components in an evacuated chamber so that you don’t get any oxidation or any un wanted substances really yeah so and you mentioned V volatization I think you you mentioned earlier which is the the the loss of various elements so one of the challenges is sort of making sure
That that composition is exactly what you expect it to be yeah so when you have a load of different components going in they’ve all got different melting temperatures and boiling points and sometimes they can cross over so you got to do a balance of melting them without boiling off other elements and
Sometimes those melting points are higher than the boiling points of other ones so it’s a hard balance to strike really yeah and how often is it that you get the composition that you actually want I think I’ve been quite lucky in getting relatively close in the compositions but if you want to go
Within like half an atomic percent it is very difficult so it’s often if you look at you know um sort of industrial materials and things there’ll be a range in these things in order to sort of account for for the fact that you know there might be some loss of of of
Various things along the way but as you say it can be challenging because I often you know very basic way of thinking about it but thinking about like cooking and things like that you know you’re you’re trying to put together a recipe for for how to make this and as you say you’ve
Got these challenges associated with things with different melting temperatures and what order to combine things and you know you can completely mess things up if you if you do it in the wrong order um and end up losing half of your half of your material um uh
Along the way so yeah so we we okay so we’ve we’ve taken our our thing we’ve melted up and now we’ve got a a small a small bar or small puck or some sort of small object a blob possibly like you know and so what what might we then do
With it what’s the what’s the next stage in the in the process yeah so then we go into testing so we can do a lot with the material that small amount of material like the amounts that Matt’s been making we then need to Define what kind of
Tests we want to um put the material through and that depends very much on the properties that we wanted to design it on so we might want to test it strength for example at room temperature or at high temperature or or a very low temperature we might want to um test its
Conductivity we might want to actually find out what is melting temperature might be because sometimes when we make new materials we might not necessarily know what that is either um so there are all sorts of different tests that we can do that we can then also compare to our
Models and see how accurate our models might the other critical thing that we do with all of these is also explore how we might be able to change the micro structure so when we make something as it comes out of whatever method we made it from it doesn’t mean it’s going to
Stay in that format so we might want to check does the micr structure change for example when we put it into operating conditions that might be high temperature might be very low temperature for example or it might be high pressure environment or it might be something else
So we might want to see how that micro structure how stable that micro structure is and what other ways we might be able to use to modify that micr structure like a cake is not a really good cake until you baked it right so
That’s a a a method that we use quite a lot to stabilize that micr structure baking our material and that we do for a lot of things for example you might want your wood to be dried in a Kil right we do that for metal but our cooking temperature might be 800° C
1,000 2,000 de C increasingly the same with our Ceramics so that cooking time is also quite critical for materials and what what sort of time scales for for some of these some of these things that’s a that’s a question that is difficult to answer because again it very much depends on our applications
Right so we might want to cook it long enough to see how we modify it for service or we might want to cook it for longer to see how it might behave in service right so if we want something to be viable for a manufacturing route we
Probably don’t want to be cooking it for longer than a day right because we want to get it into Service as quickly as possible but if we want to test how long is going to last at a particular temperature and how stable that micr structure is we might put it in a
Furnace and forget about it for about 6 months or longer and that’s I I suppose one of the the the tricky things with sample test in is that you know some of these things if we’re talking about a service alloy that’s going to go into um an aerospace component or something like
That it’s got to last for for years or I take I suppose an even more extreme example if we’re talking about um radiation damage for when we’re storing radioactive waste and we need to consider how it’s going to be stored safely underground for potentially thousands of years and I suppose one of
The sort of difficult or complexities with sample testing is working out what the correct sample testing in order to understand the environment is that can still be done in a reasonable amount of time in in a in a reasonable way in the lab and things that’s very very true and
We’ve got the models that we use to design materials we can refine them using experimental tests that don’t need to last that long so we might you mentioned materials lifing earlier exactly yeah so we can use the critical properties and we might be able to measure something over a shorter life
Cycle I guess so a shorter amount of time but then extrapolated out to what the lifetime of that particular component might be um so we’ve got a lot of different tests that operate in that way where we can accelerate effectively the damage on the material using artificial methods that don’t
Necessarily occur in nature that quickly but we can do that sort of accelerator testing for a lot of materials and nuclear is aass example so storing nuclear waste or even nuclear reactors that we don’t necessarily have the luxury of putting something in a reactor for 50 years and then waiting to see
What happens to it we do that now but 50 years ago when we were building the nuclear reactors we didn’t have that knowledge yeah um so Material Science is all about not wasting information so everything that a material has experienced is something that we can use
To help us build those models and build those models better that’s currently why I do right now with the example of nuclear materials instead of waiting to radiate your material for 50 years I use an analog of Cold Rolling so for I I cold roll my samples I flatten out my
Material at room temperature CU if I do out a high temperature I reduce the amount of damage it kneels the damage it reduce the amount of damage in my material so I do at room temperature so the damage stays within my material and I cold roll it to different levels for
Different levels of service so it’s an analog for different types of time within the nuclear reactor so that’s similar what I do to speed up time and that only took a day to do instead of weighing 50 years much more convenient SL much easier yeah so yeah as well as
Testing the samples for the physical properties what what other things do we do we look at or test so our next section which is sort of it tends to happen at the same time as our testing is understanding and characterizing the material we call it characterization that means lots of different things to
Many different people so for example we might want to going back to the Lego analogy we might want to figure out exactly in what configuration did we manage to get our little Lego blocks in our material to arrange themselves in uh so we would use for example a very very
Big microscope everybody might be used to looking at um a microscope an optical microscope that you might have at school that you can look at I don’t know a cenp or something like that there normally bits of leaf and things like that we often looked at
Or maybe I think people used to look at cells and things of various very sorts yeah yeah blood cells was one that we had a lot of actually that’s um but actually in Material Science and Engineering we use um what are known as electron microscopes so we use the
Electrons to help us actually focus at a much much finer resolution and magnify the material up to sometimes a million times magnification so we can look really down to how those atoms arrange themselves in particular columns in addition to electromicroscopy another really useful technique that we use for characterization is defraction and
Defraction is sort of giving us an idea of how the materials are how those little Leo blocks are separated from each other and that’s an area that has huge potential in helping us understand um the micr structure of the material but also has huge potential in letting us understand the material while we’re
Testing it so it’s one of the only methods that we can actually both test and characterize at the same time so we can put something at really high temperatures and just watch it evolve basically which is really helpful and very very useful which is an area that
Was say this is this is this is where I need to contain myself and and stop myself from getting too excited but we’ll we’ll have an entire episode talking about characterization later on in the series so I will contain my excitement um until then but uh but yes
Um looking at these things it’s I still find it incredible that we’re able to as you say explore those materials and look at those materials as they’re undergoing that process and see what’s taking place and that that Evolution so really help create that that strong link um between underlying structure and physical
Properties um and the the the sort of developments um that are that’s made there so yeah so um moving on then from characterization and thinking about it so um once we’ve made this material and we’ve tested its properties and we’ve found that it’s fantastic for whatever
Purpose the the the that we want it to be for Matt mentioned earlier that we then have this this problem of sort of scale up and thinking about going up a level so we’ve made a small you know a a little bar of our metal or a little
Chunk of ceramic or whatever it is that’s you know a couple of centimeters big or whatever but when we’re thinking about you know making things on an industrial scale we could be talking kilograms and meters of the material and things like that so we then have to think about that sort
Of scaleup process and and how we go about making those things so how does sort of our understanding of manufacturer and things sort of Link into this yeah manufacturing is an actually massive problem for Material Science and Engineering we can make things really really nicely in a lab we
Can control everything we can wear a nice sort of uh suit when we’re making our conductors or something like that so we don’t contaminate anything but that’s not necessarily very feasible in a normal industrial manufacturing route so that’s something that is becoming more and more prominent that we take into
Consideration in the material design cycle but traditionally we tend to decide on our ch chemistry and then fix our manufacturing which is not the most ideal way so for example in our industrial setting we might not be able to control to exactly those 10 chromium
Atoms in a 100 of iron we might get 12 or we might get eight that’s okay so we need to start thinking about how we can design the material to be tolerant to those changes so often we will see in an industrial scale up a range of compositions rather than a given
Composition which kind of helps us um give a achieve the properties but give us a range of those properties they might be in the next key thing that we need to look at is how we control that micro structure so we might control the composition and the chemistry of the
Material but how do we control the micr structure how hard we hit something for example when we’re forging it is going to change the micr structure so we need to do some manufacturing trials that will help us understand how it’s going to behave in the scale up and we can do
That on a small scale as well right so we can hit something with different forces and for different durations of time and that will give us an idea of how the micr structure evolves or we can do those cooking trials we were talking about and how long we put things in an
Oven okay this might be an oven that’s as big as a building but that’s fine we can also simulate that at a smaller scale so all of those challenges that we start facing in manufacturing actually come down to us being very clever during the design cycle and learning as much as
We possibly can about the material through that characterization and then we can start building on those and we can start combining understanding together through those models as well because I I just coming back to designing for properties and things it’s there’s there’s a a balance I suppose between these things
About you know if if we’re designing something that’s very high temperature resistant how on Earth do you then melt it in in the first place and things how do you how do you make make the make the thing in the first place and actually now as we sort of there are increasingly
Sort of creative and novel ways of sort of manufacturing things that are that are being created and as the application becomes more complex and we require more complex geometries and things like that we’re increasingly sort of seeing advancements in manufacturing techniques in order to sort of give things that
Have a particular shape and and and things like that um I wondered if you could talk bit about some of those S more advanced manufacturing processes that we often come across in Material Science yeah we’ve been coming into quite a boom of manufacturing processes actually across all the different um
Types of materials that you can think of from Ceramics to metals to even the biomaterials that are manufactured at very different conditions than traditional manufacturing processes for example one of the biggest um sort of advancements of the last 10 20 years is additive manufacturing tradition Ely we tend to
Make a lump of metal and then we machine things out of it so we take a very good cutting tool and start cutting our lump into shape bit like a sculpture right if you have a lump of marble and then you make vinus Deo we can do the same using metals or
Ceramics or anything I have the skills to make the vus Deo I’m afraid my my artistic abili is not up to that right we can get somebody else that can but additive manufacturing kind of turns that on his head rather than taking a lump of metal and taking material out of
It we’re actually printing material to the exact shape that we wanted in in the first place so additive manufacturing is what most people sort of Might more commonly have come across as as 3D printing that’s exactly right yeah so 3D printing so you can use things like a
Fine powder of material often we do that with Metals we will use a very fine powder of material um and then we put that down and run a laser of over the shape that we want and then put another layer down and run the laser over it
Again and again and again and again until we have that 3D structure and then we remove the loose powder and we’re left with our Venus Deo without having any chisling so your artistic skills don’t need to matter anymore that sounds marvelous although I will have to learn
How to sort of control the computer to get it to build the the appropriate shape so you know I suppose I I need to brush off on my computational seals in instead um and things so yeah so I I suppose that sort of brings us to sort
Of well almost the end of of our materials design so so we sort of we we took our concept we’ve uh sort of predicted what we might want to get and then we’ve we’ve made up a small amount of sample uh We’ve tested it we’ve characterized it we’ve tried building it
In various different ways and things um and so I suppose then it’s sort of time for for the material to to go out into the big wide world and go into you know a real application um but what what does that mean then in terms of because we
Need to think increasingly in the modern society about what happens towards the end of life of materials and things like that so how much do we consider with with those sorts of aspects thinking about sustainability and Recycling and sort of the the the bigger picture and the bigger backdrop in which we’re sort
Of making these materials and things yeah that’s something that’s become particularly important as we are moving towards that 2050 zero carbon Target and all of those sort of big environmental goals that we have there’s a lot of things that we need to do even after we’ve manufactured the material we need
To understand as you say how we’re going to treat it at the end of its life um and there is a lot of different ways that we might be able to extend his life for example as well so there are repair technologies that we’re working on that
Allow us to do exactly that repair the material so that we can extend his life in service a bit longer so things I additive manufacture in order to S repair bespoke parts and that’s right yeah we might want I don’t know we missed a tip out of a particular
Component so we can rebuild it without really having to remake that component or we might be able to take the material at the end of its life and remelt it back and recycle it almost into a new component often when that happens we tend to put that material into a
Component that doesn’t have quite the same properties so we end up with something that’s degraded um in the way that we think about that material so we might have designed it for an aerospace component for example and we end up seeing that material at the end of its life in an
Automotive component or a drinking can that’s often the case for aluminium or keying that is often the case for aluminium as well um so we we see that quite a lot and that’s something that we need to get better at so recycling um of metals that have gone into service or
Really any component that has gone into service is really difficult still because we have these targets that we need to meet so one thing we didn’t really talk about is qualification of a material so we might have made a material but in every single industry there will be specific testing that we
Need to perform that’s almost like a p fail test like um when you’re testing your fire alarm at home does it work or not so that that that past fail test we also have to do for materials but there might be 10 20 30 100 a thousand
Different tests that we need to pass fail on and our material will have to pass all of them so in some cases what we see with the recycling challenge is that it might pass 90% of those targets but not the remaining 10% and is that a
Matter of the material or is that a matter of our Targets in the first place so there is a lot of work going on to understand how we can refine both the targets but also understand how we can use the recycling material in better ways
And adding on to that is like you always say we’re talking about the design cycle as a going back around to it and talking about um recyclability of it there’s also legislations that now go into the initial design process so how 50 years ago when we created nuclear fion we
Don’t have leg legislation about radioactive waste and what we do with it afterwards after the post cycle now with nuclear fusion we have it where the material waste can’t last more than 10 to 100 years in the around the the Half Lives of these materials therefore we
Have to put that into the initial side side of it as well so that helps with the recyclability I I suppose there’s also a scarcity of resource things and some of some of the materials that we might want to use or some of the raw elements I should say that we might want
To use are incredibly scarce and so being able to extract them and things like that but I suppose with all of these things if you’re talking about like extraction and Recycling and things well and and with the entire materials design process in general there’s a there’s energy um associated with you
Know all of this heating that preparation when we’re doing the manufacturing Things Heating rolling like shaping uh and and all of those things and I suppose one of the other things is trying to work out how we can reduce those effects while still creating a material and a component
That’s that’s capable and and and able to withstand the the conditions it needs to be able to withand completely yeah and there is a a whole area of science uh that’s sort of between science and social science in some ways called life cycle analysis that lets us understand
Our carbon emissions or any other type of emissions uh throughout the design cycle of a material or in most cases actually the design cycle of a particular component so that we’re looking into not only how we make the material and make that component but also that component in service and at
The end of its life um and all the way through its life cycle effectively and hopefully you will have a an expert in life cycle analysis that’s going to talk a little bit more about it futureed in in a in a future episode so um one one
Thing that I thought it might be worth pointing out because this was something that sort of blew my mind or something that I hadn’t really considered but if if I today sat down and said I’ve come up with a brand new material and this is the the best things in slic bread or
Whatever for X application or whatever can you just give us an idea of the rough time scales that that are involved between sort of with this whole process between now and ultimately it’s ending up you know in a building or in a submarine or wherever it’s going to end
Up that material what what is that time scale that we’re talking about so usually that’s between 15 and 20 years and that very much depends on those qualification tests that we talked about earlier putting that material through every possible test to make sure that it’s safe can be a very timec consuming
Task and a lot of those those tests we will have to repeat many many different times to make sure that we have all the data that we need so that for example we can life that material properly so you can imagine that if you’re putting something in someone’s body like a hip
Replacement you definitely don’t want to take that chance slightly so you need to make sure that that material is going to go through all of the approvals that it needs to the same with the nuclear reactor you can’t afford for that to fail or an airplane component and we we
Have to do that very very carefully the other part of this that’s a little less scientific and a little less uh I guess honorable is uh IP right a lot of cases a lot of companies will want to secure their rights to that material and how to
Use that and if for example you decide a new material and you want to patent it well that’s at least I tell you three years I was going to say I think people often have heard of like pharmaceutical patents and things but they’re not really aware that you know you can
Patent a a metal for example or or or something like that it’s something most people they’re sort of with but patent a chemistry you can patent the manufacturing method you can patent the chemistry and the manufacturing method together and those can be three different patents right and all of that
Takes a huge amount of time because well bureaucracy right so everything adds up and that gives your sort of from design to actual service can be up to 20 years we are trying to really bring that down and there are way that we’re trying to work with for example qualifying bodies
Um and accreditation bodies to make sure that we don’t have to wait that long but the key thing that we can’t compromise on is safety y yeah so one thing that we’ve sort of been referring to throughout this is we’ve we’ve called it a cycle and so far we’ve gone from sort
Of materials design all the way to it being used and thinking about some of those those wider concerns and end of life and the the the the sort of bigger picture but then I spose suppose how how do we go sort of go back round again with with with this cycle
How do how how do we get from from there where we’ve got a something in in service to starting the whole process again all of that information is really critical on how we’re going to make that material even better in the future so we might have made our nuclear reactor out
Of a particular grade of stainless steel right but we figured out actually if we made it slightly better because we’ve learned this that and the other it will be lasting even longer all of that helps us improve our models for example and our predictive capabilities it helps us understand that component that material
And how we manufacture it better so with every iteration of that material’s design cycle we will make things better for the next one right often the minute we put a material into service it’s often out of date already right because we’ve decided that actually we’ve learned so much that we will only make
It better the next time round so for example some of the work that I was doing during my PhD it’s now coming towards realization and is going to go into service in the next five or so years right that’s very exciting it is but the we started the design cycle for
The next material 5 years ago y so already we knew we were going to be out of date and that that jet engine will need to meet some new and more exciting requirements and we knew that we could make it better so starting that cycle we often start that cycle before we’ve even
Finished the last one in the majority of cases yeah and I think one of the things then with sort of Material Science in in general is uh it com back to something we were talking about right at the very start was there’s this sort of well a lack of understanding about
What material science is but also a misconception and particularly with metalogy which we’ve been focusing a lot on today and which we’ll use as a sort of case example going forward um in the series there’s this sort of idea that you know we know everything about it already metal Metals rolled you you
Talked about the the Iron Age and the Bronze Age and things like that but actually our our understanding of them is is still and continuously developing and iterating through this cycle again and again repeating going forward absolutely so the bronze and the iron AG there just two maybe three elements on
The periodic table that periodic table is quite large and there’s quite a lot of areas that have being completely unexplored for us so Matt I think mentioned High entropy alloy so it’s going to ask him to actually go into a little bit more detail on what is now
One of the the most widely researched areas in metalogy over the last sort of 10 years or so yeah so um I mean you’ve got your conventional Alloys that if we think of a a three-part alloy so iron nickel and carbon we typically we kind of stick if you picture that in a
Triangle one element at Each corner we kind of stick to the outsides of that triangle we want one major addition with two minor additions really uh but for high entropy Alloys it’s kind of a equiatomic mix of all the elements so we’re kind of exploring that middle area
Of the triangle which has left a largely unexplored area and we’ve found some materials that can produce some fantastic properties within that space which is why we’ve got all this interest now because picking up on what what you were saying right at the beginning Kathy is that you know very often we start
With the material and Gra actually sort of Step our way towards something so you know we start with if we talk about Alloys in general people will talk about Steels which is iron with a little bit of other stuff mixed in or nickel Alloys which is nickel with a little bit of
Other stuff but here we’re going as you say we’re we’re going what happens if we mix you know all of these everything together in a in a in a Melting Pot and and and see what happens which is incredibly exciting and you know it means there are lots of different
Directions that that it can be sort of you know pulled in investigated in um and even in I mean you’re you’re in your second year of PhD now mass and you’ve been looking through the literature and things and you’ve seen I’m sure lots of different sort of applications that
People are sort of pushing towards with these different different materials and things yes there’s there’s a huge amount of applications with the high allo you’ve got like for at least what I’m doing is the excellent radiation tolerance you got high temperature applications so potentially Rivals super Alloys you got your high strength you
Got even got the low temperature uh extremely low temperature capabilities as well yes so there have been some recent studies looking at cryogenics those very cold temperatures and the super Alloys which you mentioned before they’re a particular class of material that um are often used in in Aerospace
And the potentially looking at replacing them with this this new generation assuming it works and can get through all the the tests and everything and the qualifications and everything that we’ve been talking about so far and making sure that we can make those materials which uh which are safe but it’s very
Exciting to see the sort of new area of sort of of metalogy in a new direction to sort of pushing exploring um and finding those new new properties it is yeah it’s a it’s a great area to be in currently and there’s so much we don’t
Know I think that’s the you touched upon it earlier we know very little less than 1% of what we know is actually out there and in use there’s so much that we don’t know and there’s so much that we do know but we can’t actually use yet
Uh so there’s a huge amount of potential on how we can make things better yeah that’s fantastic Kathy is there anything else that you think you know our listeners should know about materials design the materials design cycle or just Material Science something you wish you’d known when you started your journey in
Materials or or or anything like that yeah I think not taking your own empirical understanding for granted I think is the best advice that um I was ever given to be honest Miracle is the S trial and error type yeah that trial and error and that sort of oh yeah
Gut feeling or things like that they’re not necessarily true the majority of our um sort of advancement in metalogy are all entirely by accident oh no I was melting this metal and accidentally I knocked in some chromium oh no here’s stainless steel for example uh some of
The materials that I’ve been working on were also a typo most of the time I accidentally added an extra element that I wasn’t anticipating and suddenly is way better than anything else I I was depressed for months to power turned out brilliant so be open to lots of new
Ideas and be open to experimenting with things because at the end of the day that is our job We Are Scientists and Engineers we need to try a lots of different things and we shouldn’t just think that we know everything yeah it’s it exploration like you know and and
Yeah yeah exciting new spes to to explore um and things so yeah that’s fantastic Cav and Matt have you got any any other questions for for Cathy about anything that’s that’s been said or or anything that that that you wish you’d known about you know Material Science or
The material science design cycle when you started out I mean it’s not something that I wish I knew but it’s wish I knew about earlier and it’s just like how interesting and amazing the structures the micro structures of materials can look they’re so pretty there some of
Them are so pretty the evsd maps are some of the prettiest things and then I worked on a material that produced some Nano and looking like the jungle of Nano wi is just amazing ebsd is a particular type of characterization which produces very very beautiful images we’ll put
We’ll put some up um I’ll put a link in the show notes so you can you can have a look at some of these these beautiful structures and things that are created um in some of the materials and we might talk about ebsd in more detail in a
Future episode so how about you Kevy any any other thoughts going on to what Kathy said about being going with the trial and error being open about stuffing everything is what I’ve kind of learn is I thought I was going in One Direction and things just go in a
Completely different direction you have to be open to that when you go into the material cycle the design Cycles especially when you’re doing a PhD I thing is the nature of research it when when you’re at school or even undergraduate at University you know the practicals that you do are very much you
Mix A and B and it and it makes C and it works and you then get to research and you go oh I’m going to mix A and B together and seldom does it make C and normally something unexpected happens which can be good or can be bad it
Depends and then it’s about sort of you know working with that process and sort of um evolving and discovering more definitely because everything up to college is a straight line so Material Science is for the win I suppose you know it’s a Sketchbook no a straight line degree I think M just
Say Sketchbook you just go on and draw things and things just mixed together to make a pretty picture towards the end so so yes well thank you all for uh for for our our chat today and talking a bit about the materials design cycle so in this podcast in the next few episodes
What we’re going to do is we’re going to take each one of those uh sort of areas that we’ve been talking about today and go into a bit more more detail um uh about it so thinking about things like defining the problem uh materials prediction making the samples Advanced manufacturer characterization sample
Testing and then the big picture thinking about sustainability uh recycling storage and all of those sorts of things so hopefully over this podcast series we’ll get more of a chance to explore some of the things which we’ve only touched on in in in very likely um
In this episode but for now um let me thank thank my guest so thank you Kathy for joining us thanks for having me L and Carrie and Matt thank you for joining us as well thank you very much and to our listeners thank you very much
For tuning in and please do join us next time when our topic will be defining the problem thanks very much for listening if you want to join the conversation you can find us on Instagram @ materials unlock if you want to find out more about the topics that we’ve covered and
The work that we do a link can be found to our website the show notes our thanks to the advanced metallic system CDT the Henry Royce Institute and the department of material science of the University of Sheffield see you next Time