Using Grain Boundary Movement to Create a Recipe for New Materials

Professor of Materials Science and Engineering, Greg Rohrer, showcases research on polycrystalline materials and the use of high energy diffraction microscopy in the predicting of future material properties.

Transcript

00:00:04 [Music] our group studies polycrystalline materials and what i mean by that is is almost all solid materials that you use are actually made of small microscopic crystals that are all bound together at grain boundaries within the material and when you make it these grain boundaries move and after it's cooled down and you begin to

00:00:29 use it the places where the ways the grain boundaries are fixed in place affect the properties of the material this could be the strength of the material its electrical properties its optical properties and so the positions of these grain boundaries and the way they're arranged are important for the properties of the material

00:00:47 now we would like to be able to predict exactly how they move during processing because that way when the materials cooled you would be able to predict the properties and then you would have a recipe for making the material that has the properties you want unfortunately that's not possible and we are trying to learn how the grain

00:01:07 boundaries move at high temperature so that we can make these better predictions so what we did is we used a very new technique called high energy diffraction microscopy it's an x-ray microscopy technique that allows us to look inside the material and and image these grain boundaries and we recently made measurements about

00:01:27 how the grain boundaries move at high temperature and we were surprised to find that their motion is not predicted by the accepted theory in other words the uh we have a model for how the grain boundaries should move but they don't move that way and what that means is our simulations that make predictions about the structure and property of the materials are not

00:01:48 correct so these are very interesting findings to us and and it it stimulates us to look closer to understand can we develop models for how these grain boundaries move and make good predictions and we think currently there's two reasons why the theory didn't doesn't

00:02:08 work the one is very simple that all these boundaries are interconnected with each other in fact each grain boundary is connected on average to 10 other boundaries and so its motion has to be in concert with all of those others and the second is that grain boundaries are all different and i by different i mean different in a structural sense

00:02:26 and they all don't behave the same either and can't be governed by a single theory so our group is going to spend the next several years with a new grant to try to develop a better theory for how grain boundaries move at high temperature that we can then use to predict the structural development of materials

00:02:46 and their properties you