Andrew Minor1,2,Mingwei Zhang1,2,Flynn Walsh2,1,Yang Yang3,Madelyn Payne1,2,Punit Kumar2,Mark Asta1,2,Robert Ritchie1,2
University of California, Berkeley1,Lawrence Berkeley National Laboratory2,The Pennsylvania State University3
Andrew Minor1,2,Mingwei Zhang1,2,Flynn Walsh2,1,Yang Yang3,Madelyn Payne1,2,Punit Kumar2,Mark Asta1,2,Robert Ritchie1,2
University of California, Berkeley1,Lawrence Berkeley National Laboratory2,The Pennsylvania State University3
This talk will describe our recent results utilizing energy filtered diffraction, 4D-STEM and in situ TEM nanomechanical testing and ex situ nanoindentation that provide insight into multiscale deformation phenomena in the CrCoNi medium entropy alloy. Using energy-filtered TEM and HRSTEM techniques it is possible to directly image, and therefore quantitatively assess, SRO and its effect on mechanical properties. In order to understand the effect of SRO in terms of the evolution of plasticity at different stages, the technique of 4D-STEM was used during in situ deformation and fracture experiments. 4D-STEM can provide both real-space imaging and diffraction analysis during <i>in situ</i> testing, making it possible to perform strain mapping via diffraction pattern analysis during in-situ deformation in a TEM. The diffraction patterns are used to identify defects and map relative strain, while the images formed by using virtual apertures provide microstructural context for the analysis. Our results from electron microscopy are then correlated with mechanical testing including nanoindentation to examine how SRO evolves with different processing conditions. Lastly, we will consider the role of both SRO and planar defects in the both the mechanical response as well as structural determination via electron diffraction as a function of heat treatment in the CrCoNi MEA.