Vacuum tribological behaviors of CoCrFeNi high entropy alloy at elevated temperatures

Abstract High entropy alloys (HEAs) are an important candidate for high temperature mechanical systems. Here, effects of atmosphere, temperature and counterparts on the vacuum tribological behaviors of CoCrFeNi HEA fabricated by spark plasma sintering were systematically studied. Comparison of tribological behaviors in vacuum and air indicated that tribo-oxidation is detrimental to the wear resistance of CoCrFeNi HEA within temperature range 25 - 400 °C, but positive at 600 and 800 °C. The CoCrFeNi HEA obtains relatively low wear in vacuum when low testing temperatures and heterogeneous counterface are selected. The wear resistance of CoCrFeNi HEA in vacuum is superior or comparable to the steel and intermetallics.