Local chemical fluctuation mediated ductility in body-centered-cubic high-entropy alloys

High-entropy alloys (HEAs) open up a new horizon for discovering un-explored mechanical properties and deformation mechanisms. Local chemical fluctuations (LCFs) in HEAs were found to have significant influences on their mechanical performance, however, the underlying origins remain unclear. In this work, direct dynamic observation of the interaction between LCFs and dislocations was captured by in situ transmission electron microscopy in a ductile body-centered-cubic (BCC) HfNbTiZr HEA under loading. The observed dislocation pinning induced by LCFs contributes to the increment not only in the strength but also in the ductility due to strongly promoted dislocation interaction. The observed local double cross-slips caused by the LCFs distribute dislocations onto various atomic planes homogenously, which is also beneficial for ductilization in HfNbTiZr. Our findings not only shed light on the understanding of deformation mechanisms of HEAs, but also provide a new perspective to design ductile BCC HEAs.

Automated summary

This study captured the dynamic interaction between LCFs and dislocations in ductile BCC HfNbTiZr HEAs, demonstrating how LCFs influence strength and ductility by promoting dislocation interaction. The observed double cross-slips caused by LCFs homogenously distribute dislocations onto various atomic planes, contributing to ductilization in HfNbTiZr. These findings offer insights into the deformation mechanisms of HEAs and suggest new strategies for designing ductile BCC HEAs.