Creep Behaviors of CrMnFeCoNi High Entropy Alloy at Intermediate Temperatures

Abstract

In this study, creep properties and fracture behavior of CrMnFeCoNi high entropy alloy (HEA) were studied at intermediate temperatures. The invert-type transient primary creep behaviors were observed in CrMnFeCoNi high entropy alloy. Creep behaviors of HEA are similar to those of class I solid solution alloys. The transient creep curves upon increase of stress by 5MPa in the steady state creep region did not change much except the sudden strain increase. And, no decrease of creep rate was observed upon increase of stress. Instead, the slightly invert transient creep or almost straight creep curves were observed, supporting the high friction stress. CrMnFeCoNi high entropy alloy has a stress exponent of 3.75 and the creep activation energy was calculated to be 278KJ/mole. The fracture strain increased from 1.3 to 1.6 with the decrease of stress from 96 MPa to 48MPa. The lower stress exponent along with the invert type primary creep curves strongly suggest that the creep of CrMnFeCoNi high entropy alloy at 600°C~650°C occurs by a glide controlled process.