Nene S S, Frank M, Liu K, Mishra R S, McWilliams B A, Cho K C
Center for Friction Stir Processing, Department of Materials Science and Engineering, University of North Texas, Denton, Texas, 76207, USA.
Weapons and Materials Research Directorate, U.S. Army Research Laboratory, Aberdeen Proving Grounds, MD, 21005, USA.
Sci Rep. 2018 Jul 2;8(1):9920. doi: 10.1038/s41598-018-28383-0.
Design of multi-phase high entropy alloys uses metastability of phases to tune the strain accommodation by favoring transformation and/or twinning during deformation. Inspired by this, here we present Si containing dual phase FeMnCoCrSi high entropy alloy (DP-5Si-HEA) exhibiting very high strength (1.15 GPa) and work hardening (WH) ability. The addition of Si in DP-5Si-HEA decreased the stability of f.c.c. (γ) matrix thereby promoting pronounced transformation induced plastic deformation in both as-cast and grain refined DP-5Si-HEAs. Higher yet sustained WH ability in fine grained DP-5Si-HEA is associated with the uniform strain partitioning among the metastable γ phase and resultant h.c.p. (ε) phase thereby resulting in total elongation of 12%. Hence, design of dual phase HEAs for improved strength and work hardenability can be attained by tuning the metastability of γ matrix through proper choice of alloy chemistry from the abundant compositional space of HEAs.
多相高熵合金的设计利用相的亚稳性，通过在变形过程中促进相变和/或孪生来调节应变适应性。受此启发，我们在此展示了含硅双相FeMnCoCrSi高熵合金（DP-5Si-HEA），其具有非常高的强度（1.15吉帕）和加工硬化（WH）能力。在DP-5Si-HEA中添加硅降低了面心立方（f.c.c.，γ）基体的稳定性，从而在铸态和晶粒细化的DP-5Si-HEA中均促进了明显的相变诱发塑性变形。细晶DP-5Si-HEA中更高且持续的WH能力与亚稳γ相和析出的密排六方（h.c.p.，ε）相之间的均匀应变分配有关，从而使总伸长率达到12%。因此，通过从高熵合金丰富的成分空间中适当选择合金化学成分来调节γ基体的亚稳性，可以实现用于提高强度和加工硬化性的双相高熵合金的设计。
