Quantitative analysis of multiple deformation mechanisms in NiCrCoFe high-entropy alloy

Abstract

Multiple deformation mechanisms were often observed during the deformation processes of high-entropy alloys (HEAs), but the quantitative analysis of the contribution of different deformation mechanisms to the total deformation is few involved. In this work, the multiple deformation mechanisms in NiCoCrFe HEA are studied by molecular dynamics (MD) method. The average flow stress transforms from Hall-Petch (HP) relationship to inverse Hall-Petch (IHP) relationship with grain refinement at critical grain size (dc ≈ 27.31 nm). And the microstructural evolutions of microstructures during the deformation process are revealed by means of the crystal-analysis-tool (CAT). The contributions of various microstructural configurations to the total deformation are systematically studied by means of post-processing metrics. In the strengthening regime, the deformation mechanisms are dominated by stacking fault, grain boundary (GB) activity, and HCP martensitic transformation, accompanied with twinning and dislocation. In the softening regime, the deformation mechanisms are dominated by GB activity and stacking fault. The deformation mechanisms revealed according to the percentages of total strain accommodated by various microstructural configurations is more accurate than their atomic fractions. These results would provide an accurate and deep insight into the multiple deformation mechanisms of HEAs.