Transition of plastic deformation mechanisms governed by spacing of nano-precipitates in a high entropy alloy

Optimization of the plastic deformation mechanism by reducing the stacking fault energy (SFE) of alloys through precipitation is a promising method to improve the strength-plasticity synergy of high-entropy alloys (HEAs). In this study, two HEAs with the same composition but different deformation mechanisms were developed by controlling precipitation. The dislocation plane slip and stacking fault (SF)-dominated deformation were tuned to be the main deformation mechanisms in the two HEAs. The transition of the deformation mechanism was induced by a change in the spacing (lambda) of nano-precipitates. Only at sufficiently small lambda (< 6 nm), the regions with reduced SFE around nano-precipitates connected and overlapped owing to the depletion of Ni and Nb, reducing the SFE of the whole matrix. This promoted the formation of SFs during deformation, thereby simul-taneously improving strength and plasticity.

Automated summary

Controlling precipitation can tune the deformation mechanism of high-entropy alloys, thereby improving the synergy between strength and plasticity.