Orientation dependent plastic localization in the refractory high entropy alloy HfNbTaTiZr at room temperature

A statistical and quantitative perspective on the incipient slip localization behavior of the HfNbTaTiZr refractory high entropy alloy is presented, after monotonic tensile testing at room temperature. High-resolution digital image correlation (HR-DIC) data collected in the scanning electron microscope (SEM) is coupled with electron back-scattered diffraction (EBSD) over millimeter-scale fields of view containing over a hundred crystal orientations. Two populations of grains are identified with respect to their slip localization: a vast majority of the grains exhibit a high density of apparently straight slip bands of low intensity, while the remaining grains show few but very intense and wavy slip bands at the mesoscopic scale. The slip localization behavior is strongly correlated to the crystal orientation with respect to the loading direction. This behavior is discussed with regard to dislocation glide and cross-slip processes.