Madelyn Payne1,2,Mingwei Zhang1,Punit Kumar1,Mark Asta1,2,Robert Ritchie1,2,Andrew Minor1,2
Lawrence Berkeley National Laboratory1,University of California, Berkeley2
Madelyn Payne1,2,Mingwei Zhang1,Punit Kumar1,Mark Asta1,2,Robert Ritchie1,2,Andrew Minor1,2
Lawrence Berkeley National Laboratory1,University of California, Berkeley2
High-entropy alloys (HEAs) have attracted attention from the metallurgy community due to their exceptional properties, often at both high and low temperatures. Transmission electron microscopy (TEM) provides a means to investigate various deformation mechanisms producing exceptional properties in both face-centered cubic (fcc) and body-centered cubic (bcc) HEA systems. High-resolution TEM and four-dimensional scanning electron microscopy (4D-STEM) analysis reveal an extended sequence of deformation mechanisms that produce exceptional fracture toughness. Spatially-resolved structural information from 4D-STEM datasets uncover how stacking faults, hcp laths, and nanotwins operate synergistically to prolong strain-hardening. Furthermore, TEM imaging of in-situ tensile straining of HEAs demonstrates dislocation mobility mechanisms at both room temperature and elevated temperatures, providing insight to differences of deformation properties at various temperatures. Here we report both ex situ and in situ TEM observations of deformation mechanisms in both fcc HEA and bcc refractory HEAs across a wide range of temperatures.