Orientation-related twinning and dislocation glide in a Cantor High Entropy Alloy at room and cryogenic temperature studied by in situ TEM straining

TL;DR

This study investigates how twinning and dislocation glide in a high entropy alloy depend on temperature and crystal orientation, revealing their joint occurrence in polycrystals at early deformation stages.

Contribution

It provides new insights into the temperature and orientation dependence of twinning and dislocation activity in a Cantor high entropy alloy using in situ TEM.

Findings

Twinning is more frequent at cryogenic temperatures.

Twinning prevalence depends mainly on crystal orientation.

Twinning and dislocation plasticity can occur together early in deformation.

Abstract

In situ straining experiments were performed in a TEM on an equimolar CoCrFeMnNi (Cantor) high entropy alloy at room and cryogenic temperature. Perfect and partial dislocation activity were recorded in both cases. Twinning directly follows the development of partial dislocation shearing that has various origins (perfect dislocation splitting, anchoring). It is shown that, although twinning is more frequently observed at liquid nitrogen temperature, its prevalence depends mainly on crystal orientation. As a result, twinning and perfect dislocation plasticity are likely to occur jointly in random oriented polycrystals, even at early stages of deformation.