On the mechanisms of nucleation and growth of deformation twins in equiatomic CrCoNi medium-entropy alloy
4 October 2019
Campus Groenenborger, lokaal U.408 - Groenenborgerlaan 171 - 2018 antwerpen (route: UAntwerpen, Campus Groenenborger
11:30 AM - 12:30 PM
Organization / co-organization:
Friday Lecture by Lipeng Ding, EMAT
About the lecture
High-entropy alloys (HEA) and medium-entropy alloys (MEA), containing multiple principal elements typically with equiatomic or near-equiatomic ratios, have drawn considerable attention due to their promising performances. However, the elementary mechanisms controlling the deformation and fracture of this new class of alloys are still poorly understood.
In the present study, the nucleation and growth mechanisms of deformation twins in a medium-entropy CrCoNi alloy were investigated using transmission electron microscopy. It was revealed that planar dislocation slip is the dominant deformation mode at the early stage of deformation.
With increasing strain, careful analysis of the dislocations confirms that two different mechanisms are responsible for the nucleation of deformation twins. It seems that the simultaneous activation of these two mechanisms related to the existence of extended Shockley partial dislocations is quite unique. Furthermore, such features seem to play an important role in increasing the work hardening rate of this alloy.