Effect of Al and Ti additions on the high cycle fatigue behavior of CoCrNi‐based medium‐entropy alloys at room and high temperatures

Abstract

AbstractFor the application of medium‐entropy alloys (MEAs) in engineering, high cycle fatigue behavior of CoCrNi‐based MEAs with different Al and Ti additions was investigated at room temperature (RT) and 350°C in this study. When Al and Ti contents were increased from 1 to 4 at.% and 2 to 3 at.%, respectively, yield and fatigue strength increased by 70% and 43%, respectively, hardness and ultimate tensile strength increased by 40%, and fracture elongation was >37%. Between RT and 350°C, the effect of temperature on the tensile and fatigue strength was not significant. The fatigue crack propagation resistance increased with increase in Al and Ti contents. Based on the fatigue strength determined in the study, fatigue life prediction equations were derived. Microstructure analysis indicated that higher tensile and fatigue strength were attributed to uniformly distributed precipitates of nanoscale L12 particles formed in the FCC matrix.