Advances in Multi-Principal Elements Alloys X: Structures and Modeling: Poster Session
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; Jennifer Carter, Case Western Reserve University; Srivatsan Tirumalai; Xie Xie, FCA US LLC; Gongyao Wang, Alcoa Technical Center

Monday 5:30 PM
February 28, 2022
Room: Exhibit Hall C
Location: Anaheim Convention Center


A-12: KMC Modeling of Screw Dislocation Strength in Equiatomic bcc Refractory Alloys: Xinran Zhou1; Jaime Marian1; Sicong He1; 1UCLA
     Refractory multi-element alloys with bcc structure display aremarkable strength at high temperatures, which cannot be explained by the standard model of bcc plasticity based on thermally-activated screw dislocation motion. Several works point to chemical energy fluctuations as an essential aspect of RMEA strength that is not captured by standard models. Our work quantifies the contribution of screw dislocations to the strength of equiatomic Nb-Ta-V alloys using a kMC model. We find that chemical energy fluctuations along the dislocation line lead to measurable concentrations of kinks in equilibrium in a wide temperature range. A fraction of these form cross-kink configurations, which are found to control screw dislocation motion and material strength. Our simulations confirm that (i) the evolution of cross kinks and self-pinning are strong contributors to the strength of this alloy at low temperature, and (ii) screw dislocation plasticity alone cannot explain the high temperature strength of bcc RMEA.

A-13: Phase Transition Zones in Compositionally Complex Alloy Films: Daniel Goodelman1; Andrea Hodge1; 1University of Southern California
    Compositionally complex alloys (CCAs), a subset of multi-principal element alloys (MPEAs), have garnered significant attention due to their notable mechanical and physical properties. Previous studies have examined the influence of varying elemental composition on phase transitions in these materials, however they have prioritized pseudo-binary arrangements in which one “large” element is varied amongst several “small” elements. In this work, magnetron co-sputtering is employed to vary the composition of two “large” elements, Al and Ti, within the AlCrFeNiTi and AlCoFeNiTi CCA families to examine their influence on phase morphology transitions. Additionally, Cr is substituted with similarly sized but structurally dissimilar Co to observe the effect of the “small” elements on the overall microstructure. Furthermore, nanoindentation is performed to study the effect of crystallographic transitions on mechanical properties. The phase transitions are then mapped for each system to develop a guide for future alloy development.