Microstructure stability and oxidation behaviour of (FeCoNiMo)₉₀(Al/Cr)₁₀ high-entropy alloys

ABSTRACT

Simple ordered L1₂ phase and complex ordered µ phase were found in the (FeCoNiMo)₉₀Al₁₀ alloy, while disordered FCC and µ phases were detected in the (FeCoNiMo)₉₀Cr₁₀ alloy. After annealing at 900°C, nano-size precipitates were observed in the L1₂ phase, and splitting and spheroidisation were occurred in some regions of the eutectic structures in the (FeCoNiMo)₉₀Cr₁₀ alloy. After holding for 100 h at 900°C, (FeCoNiMo)₉₀Al₁₀ alloy showed an excellent hardness resistance. The oxidation kinetics of both (FeCoNiMo)₉₀Al₁₀ and (FeCoNiMo)₉₀Cr₁₀ alloys followed a parabolic rate law at 900°C. An external layer of Al₂O₃ and an underlying MoO₂ subscale were found in the (FeCoNiMo)₉₀Al₁₀ alloy. A semi-continuous oxide layer of MoO₂ and Cr₂O₃ was observed in the (FeCoNiMo)₉₀Cr₁₀ alloy.

KEYWORDS:

• High entropy alloys
• microstructure
• property
• stability
• oxidation resistance
• phases
• hardness resistance
• oxidation kinetics

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

N. Liu http://orcid.org/0000-0003-2020-9226

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [Grant Number 51201072]; Natural Science Foundation of Jiangsu Province: [Grant Number BK20161270].