Strain-Rate Sensitive Deformation Behavior under Tension and Compression of Al0.3CrFeCoNiMo0.2

Abstract

Herein, the strain-rate sensitive deformation behavior of a sintered Al- and Mo-modified CrFeCoNi high-entropy alloy (HEA) is focused. The sintered microstructure is investigated using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction. It was found that after sintering, the microstructure is of very low porosity (<1%) and consists of an ultrafine Mo- and Cr-rich σ phase embedded in a fine-grained face-centered cubic (FCC) matrix. Electron microscopy reveals another secondary phase in which Al and Ni are concentrated. For a detailed discussion of the deformation behavior under tension and compression, tensile and compression tests were conducted at strain rates of 10−3, 10, and 102 s−1. Strain-rate sensitive deformation behavior in terms of strength is observed. The strain hardening rates show no significant strain rate sensitivity (SRS) up to strain rates of 10 s−1. However, at higher strain rates and under compressive loading, a distinctly increased strain hardening rate is found. Tension/compression asymmetry is determined since the SRS value m is twice as high under compression than under tension.