The material design strategy of combining multiple elements in near-equimolar ratios has spearheaded the emergence of high-entropy alloys (HEAs), an exciting class of materials with exceptional engineering properties. In the talk, I will present our recent efforts in developing first-principles methods to understand, design, and discover new HEAs.
Random mixing of atoms has been widely assumed in multi-principal element solid solutions. However, both experimental and computational evidence suggests the existence of preferred atomic pairs, or short-range order (SRO), in many solid-solution HEAs. We employed an integrated first-principles and experimental approach to investigate the atomic characteristics of SRO in the refractory NbTaTiV and NbTaTiVZr HEA systems. Predictions from first-principles statistical modeling were reproduced with experimental observations. The existence of SRO correlates with distinct lattice distortion in these HEAs, creating new structural features that can be designed for better mechanical properties.
Elastic properties are important criteria for engineering material design. The elastic constants of a material provide a description of the response of the material to external stresses in the elastic limit, which provides fundamental insight into the nature of the bonding and is known to correlate with many mechanical properties. In the talk, I will also discuss the integration of first-principles calculations, high-throughput methods, and machine learning to understand the elasticity of HEAs spanning a broad chemical space. In particular, the discovery of a unique temperature dependency of elastic anisotropy in the NbTaTiV HEA will be described.
Dr. Wei Chen is an Assistant Professor in the Department of Mechanical, Materials, and Aerospace Engineering at Illinois Institute of Technology. He received his Ph.D. in Materials Science and Engineering from Northwestern University and conducted postdoctoral research with the Materials Project at the Lawrence Berkeley National Laboratory. His research is in the broad field of computational materials science. He is the author of several highly-cited materials genomic datasets for materials design and contributed to the rapid adoption of data-driven methodologies for materials discovery. Since joining Illinois Institute of Technology, his research has been focused on developing first-principles methods for accelerated design and discovery of materials for critical applications, including Na-ion batteries for energy storage, electrocatalysts for CO2 sequestration, and high-entropy alloys for novel structural and functional properties. He was the recipient of an NSF CAREER award for his research on high-entropy alloys.