High Entropy Alloys IX: Alloy Development and Properties: Alloy Development and Application I
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Alloy Phases Committee, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Peter Liaw, University of Tennessee; Michael Gao, National Energy Technology Laboratory; E-Wen Huang, National Chiao Tung University; Srivatsan Tirumalai; Xie Xie, FCA US LLC; Gongyao Wang, Globus Medical
Monday 8:30 AM
March 15, 2021
Room: RM 10
Location: TMS2021 Virtual
Session Chair: Peter Liaw, The University of Tennesee; Carl Koch, North Carolina State Univ
8:30 AM Keynote
Nanostructured High Entropy Alloys: A Review: Carl Koch1; 1North Carolina State University
Nanostructured materials is now a mature research area. High entropy alloys is a more recent area of interest in materials science. This talk will review research on nanostructured high entropy alloys with emphasis on those made by mechanical alloying and high pressure torsion. The paper will begin with a discussion of the seminal research of B. S. Murty and co-workers who first produced nanocrystalline high entropy alloys. This will be followed by a discussion of research of mainly 3d transition metal alloys made nanocrystalline by mechanical alloying. Research on the well-studied Cantor alloy, from the literature and the author’s laboratory will be presented. The possibility of high entropy alloys enhancing the thermal stability of nanocrystalline grain size will be discussed. The author’s and co-worker’s research on a low density high entropy alloy with single phase fcc or hcp structure and an extremely high strength (hardness)-to-weight ratio will be described.
9:00 AM Invited
Exploring Benefits of Metastability in High Entropy Alloys: C. Tasan1; Shaolou Wei1; 1Massachusetts Institute of Technology
Decades of efforts in high-strength alloy investigations has well documented the significant role of strain-induced martensitic transformation in mechanical performance advancement (namely, the transformation induced plasticity effect, TRIP). Albeit TRIP-assisted alloys benefit from stress delocalization and thereby deformation homogenization resulting from the transformation, the resultant product, martensite, is yet problematic: its extensive defects density and hardenability discrepancy with the adjacent austenite can lead to local embrittlement and hence fracture. Here in this talk, new findings in three high entropy alloys (HEA), which are Ti-, Fe- and Co-based, will be presented and discussed. The investigations of these multi-phase alloys demonstrate that unexpected mechanical property benefits can be achieved upon pushing the limits of phase stability in HEAs.
9:25 AM Invited
Opportunities and Trends in High Entropy Alloys: A Materials Science Perspective from the National Science Foundation: Judith Yang1; 1National Science Foundation
High entropy alloys (HEA) are gaining considerable scientific interest as they can possess unusual and outstanding properties due to their unique multiprincipal element compositions. Understanding the fundamental processing-microstructure-property relationships in HEA is also of significant interest at the US National Science Foundation (NSF) . This presentation will cover NSF's efforts to support basic research in this area from the perspective of the Metals and Metallic Nanostructure (MMN) program within the Division of Materials Research (DMR) at NSF. The inherently multidisciplinary nature of these scientific questions, and the opportunities to address them, will be covered from the funding agency viewpoint.
9:50 AM Invited
Linking the Metallurgy of Multiple Principal Element Alloys to Properties: David Shifler1; 1Office of Naval Research
The concept of multi-principal element alloys (MPEAs) opens new compositional spaces leading to millions of unexplored alloy possibilities. How do these alloy configurational differences influence properties and behavior, and what variables control such alloy properties? This requires establishment of new theories to explain and predict solid solution strengthening, surface passivity, or functional properties in MPEAs. Recent developments in efficient, high-throughput computational tools and high throughput experiments for structural materials and screening alloys for passivity studies provide the foundation for new materials discoveries. These offer high throughput calculations of ground state crystal structures and the distorted atomic positions in MPEAs, for exploring diffusion and dislocation motion, and passivity, and how configurations lead to different functional and structural properties and how are those properties may be related to chemical composition and processing variables. This promises to activate data-driven studies in MPEAs.
10:15 AM Invited
Order and Disorder in Amorphous and High-entropy Alloys: Yong Zhang1; Xuehui Yan2; 1University of Science and Technology Beijing; 2University of Science and Technology Beijing
Order and disorder are the dominant parameters in the materials science, as entropy is a measure of the disorder, thus the high-entropy alloys and amorphous alloys, which are mainly focused on their order and disorder, the high entropy alloys are dominated by the chemical disorder, while the amorphous alloys are dominated by the topological disorder. Intermetallic compounds are usually chemically ordered phases. Materials development of the human being is a process of the increasing of varies disorders or entropy to meet the complex performance conditions. The criteria to define the high entropy alloys also are changing from 1.62R, 1.5R, to 1R, R is the gas constant. Medium entropy can be those alloys with lower entropy than that of the high entropy alloys, but they are developed by using the conception of high entropy alloys. Most potential high-entropy alloys for the harsh environments are, NbTiAlSiN4, NbTiAlSiWN5, etc.