Collective Dislocation Motion and Localization of Slip in an HEA

Alloy design with equimolar compositions of a number of elements has become a disruptive approach to materials discovery. In selected cases, multi-component metallic mixtures, also referred to as high-entropy alloys, can be cast into single phase solid solutions that due to their topological and chemical complexity can exhibit a suite of remarkable thermo-mechanical properties. This structural and chemical complexity is thought to have distinct consequences for local point and line defect mobility, both of which control the macroscopic response of the material. Here we focus on the collective dislocation motion of a fcc single-phase solid solution of the well-known AlCoCrFeNi alloy with the aim of revealing how lattice distortions may affect depinning and subsequent motion of dislocations (JOM 70, (2018) 1088). We furthermore track in-situ in an electron microscope the spatial localization of slip that allows assessing how depinning and subsequent collective dislocation behavior is affected by the systems microplastic deformation history (Physical Review Materials 5, (2021) 043604). We compare our results to pure single element metals and conclude that differences primarily are found in the fine details of the time-resolved velocity signature rather than in the averaged quantities, suggesting at the coarse-grained level a very similar collective dislocation velocity in the investigated pure and compositionally complex metals.