The role of Nb on the high temperature oxidation behavior of CoCrFeMnNbxNi high-entropy alloys

• DOI: 10.1016/j.corsci.2019.07.012
• Publication Date: 2019-07-09T15:03:33Z
• Authors: Dong Huang; Jiashen Lu; Yanxin Zhuang; Chunxu Tian; Yibo Li
• Keywords: Laves phase; High-Entropy Alloys; Internal oxidation; High-Temperature Corrosion

Abstract The high temperature oxidation behavior of CoCrFeMnNbxNi high-entropy alloys in air was studied. As-cast CoCrFeMnNb0.25Ni alloy is a duplex-phase structure of FCC plus Laves phase. The oxidation kinetics of alloys followed parabolic rate law and the corresponding oxidation rate constants were calculated. In the oxidation process, Nb plays a dual role: On the one hand, the new Laves phase at the oxidation scale/alloy interface hinders the outward diffusion of active metal cations and improves the oxidation resistance; On the other hand, the Laves phase inside the alloy becomes the channel for oxygen ions to diffuse inward and forms internal oxidation.