High Entropy Alloys (HEAs) are a new class of random solid-solution alloys that present impressive mechanical properties, making them attractive for many applications. However, the physical mechanisms underlying the strengthening of HEAs remain unknown.
The goal of this project is to investigate the effects of solutes on plasticity in body-centered cubic (BCC) HEAs.
We will use numerical simulations based on ab initio electronic structure calculations in order to improve our fundamental understanding of solute strengthening in BCC HEAs. We will focus on the interaction of screw dislocations, which control plasticity in crystalline materials, with interstitial carbon/nitrogen/oxygen solutes in the Nb-Ta-Ti-Hf-Zr alloy.
These simulations at the atomic scale will make it possible to describe the dislocation core structures and energies in the presence of solutes in HEAs. We will build on recent preliminary high-temperature observations by in-situ straining experiments in a transmission electron microscope in the Nb-Ta-Ti-Hf-Zr alloy, evidencing a thermally-activated motion of straight screw dislocations in the high-temperature regime.
The present project will enable to investigate whether the reappearance of the Peierls mechanism at high temperature in this HEA is related to the interaction of screw dislocations with the impurities present in this HEA. This work will be performed within the framework of the EUROfusion European consortium.