Studying Grain Boundary Regions in Polycrystalline Tantalum using Spherical Nano-indentation

Presented by Olajesu Olanrewaju, a graduate student at Iowa State University and 2024 participant of the ASM Student Speaking Symposium (S3). To learn more about this contest, please visit https://bit.ly/2WXL3WV



Full Presentation Title: Studying Grain Boundary Regions in Polycrystalline Tantalum using Spherical Nano-indentation


Our NSF-DMREF project seeks to fundamentally change how we approach the design and manufacture of materials by controlling both defect/feature character and internal stress state to achieve a 30% reduction in accumulated damage. Our initial efforts describe the utility of spherical nanoindentation stress-strain curves to characterize the local mechanical behavior within individual grains of Ta (our model BCC refractory material) and near grain boundaries of polycrystalline Ta samples. Using a series of examples, we demonstrate the capabilities of our data analysis procedures in a) characterizing the local indentation yield strengths in individual grains of deformed polycrystalline metallic samples and relating them to increases in the local slip resistances; b) correlating the stored energy differences of individual grains to their Taylor factors as a function of imposed cold work; and c) understanding the role of interfaces such as grain boundaries in the deformation of a multi-phase polycrystalline sample.