Mechanical properties and deformation mechanisms in CoCrFeMnNi high entropy alloys: A molecular dynamics study
Journal
Materials Chemistry and Physics
Journal Volume
271
Date Issued
2021
Author(s)
Abstract
We used molecular dynamics simulations to investigate the relationship between mechanical properties and deformation mechanisms in CoCrFeMnNi alloys having different compositions. According to deformation twinning activity, the deformation mechanisms in the different CoCrFeMnNi compositions under tensile loading can be classified into three major categories: easy-shear (ES), inter-locks (IL) and bulk hexagonal closed packed (hcp) transformation (BH). We found that the compositions with ES were more likely to rupture early because of the short and fragmented twins. The compositions following the IL pattern promoted the movement of interlocking stacking faults in the twin boundaries that could prolong tensile deformation. Moreover, BH could further increase ductility because the hcp transformation could absorb and dissipate the stacking faults. Experimental observations of immobile stacking-fault networks that impede dislocation motion and further provide preferred sites for the formation of the hcp phase were commonly found in the ES, IL and BH patterns. The calculated intrinsic stacking fault energies of CoCrFeMnNi and CoCrFeNi were consistent with the experimental measurements. The combination of high unstable stacking fault energy with the formation of the IL pattern results in high strength and high ductility in the CoCrFeMnNi HEA system. ? 2021 Elsevier B.V.
Subjects
Deformation
Ductility
High entropy alloys
Mechanism
Molecular dynamics
Strength
Chromium alloys
Cobalt alloys
Entropy
High-entropy alloys
Iron alloys
Manganese alloys
Mechanisms
Stacking faults
Twinning
Deformation mechanism
Deformation twinning
Dynamic studies
Dynamics simulation
Fault energy
Mechanical deformation
Property
Stackings
Type
journal article