Low-cycle fatigue properties of CoCrFeMnNi high-entropy alloy compared with its conventional counterparts

The behavior of CrCoFeMnNi high-entropy alloy (Cantor) during cyclic deformation at room temperature was compared with those of a twinning-induced plasticity (TWIP) steel and 304 stainless steel (SS304). The three materials with similar grain sizes (-65 um) were made by controlled heat treatment and tested to evaluate tensile and low-cycle fatigue (LCF) properties. The tensile strength and ductility of Cantor were much lower than those of TWIP steel and SS304. Cantor and TWIP steel revealed cyclic hardening and then softening; SS304 showed secondary hardening at the latest stage of cyclic deformation due to formation of M-martensite, which led to a significant decrease in its LCF life. At high total strain amplitudes >0.4% LCF life was longer in Cantor than in SS304, but shorter than in TWIP steel. However, at total strain amplitudes <= 0.4%, Cantor showed the shortest LCF life. It was found that the Coffin-Manson plot of Cantor followed the trend of TWIP steel rather than that of SS304. Microstructural analysis of the Cantor with increasing cycles revealed the formation of twins and well-defined cell structures, the latter of which is the evidence of wavy slip.