Effects of alloying on deformation twinning in high entropy alloys

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:763

Article

Li, Wei^1,2  Fan, Haidong¹  Tang, Jing¹  Wang, Qingyuan¹  Zhang, Xu³  El-Awady, Jaafar A.² 

[1] Sichuan Univ, Dept Mech, Chengdu 610065, Sichuan, Peoples R China

[2] Johns Hopkins Univ, Dept Mech Engn, Whiting Sch Engn, Baltimore, MD 21218 USA

[3] Southwest Jiaotong Univ, Sch Mech & Engn, Appl Mech & Struct Safety Key Lab Sichuan Prov, Chengdu 610031, Sichuan, Peoples R China

关键词: High entropy alloys;    Twin nucleation stress;    Molecular dynamics;    Nanocrystals;    Atomic strain and stress;   

DOI  :  10.1016/j.msea.2019.138143

来源: Elsevier

【 摘 要 】

In the current work, molecular dynamics (MD) simulations were employed to model the compressive property of FCC (face centered cubic) Al0.25CoFeNiCu0.75 high entropy alloy (HEA) nanopillars. For comparison the binary, ternary and quaternary derivatives based on Ni-Cu-Fe-Co-Al system along with pure Ni were investigated. The twin nucleation and migration stress, atomic strain and stress and generalized planar faults energy (GPFE) of the compositions were calculated. The simulation results suggest that plastic deformation of all nanopillars is mediated by deformation twinning, but both the yield strength and flow stress decrease with the increase in the number of alloying elements, implying the decrease in the twin nucleation and migration stresses, respectively. The atomic strain and stress, increasing with the addition of alloying elements, provide direct evidences at atomic scale for the severe lattice distortion resulting in the decrease in stacking fault energy (SFE) and twin boundary energy as shown in the GPFE curves. The SFE of Al0.25CoFeNiCu0.75 HEA is 16mJ/m(2). The twinnability of the studied compositions also increases with the addition of alloying elements, so twinning deformation dominates in the current nanocrystals.

【 授权许可】

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