A Hf-doped dual-phase high-entropy alloy: phase evolution and wear features

• Published in: Rare metals Vol. 43; no. 1; pp. 324 - 333
• Main Authors: Ren, Hao, Chen, Rui-Run, Gao, Xue-Feng, Liu, Tong, Qin, Gang, Chiu, Yu-Lung, Wu, Shi-Ping, Guo, Jing-Jie
• Format: Journal Article
• Language: English
• Published: Beijing Nonferrous Metals Society of China 01.01.2024; Springer Nature B.V
• Subjects: Abrasive wear; Adhesive wear; Aluminum oxide; Biomaterials; Chemistry and Materials Science; Energy; Grain refinement; High entropy alloys; Hypoeutectic structures; Laves phase; Materials Engineering; Materials Science; Metallic Materials; Microstructure; Nanoscale Science and Technology; Original Article; Phase composition; Physical Chemistry; Solid phases; Solid solutions; Solution strengthening; Wear mechanisms; Wear rate; Wear mechanism; High entropy alloy; Hardness; Laves phase
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-023-02410-0

Initially defined high entropy alloys (HEAs) usually exhibit a single-phase solid-solution structure. However, two and/or more types of phases in HEAs possibly induce the desired microstructure features, which contribute to improving the wear properties of HEAs. Here, we prepare a series of (AlCoCrFeNi) 100− x Hf x ( x  = 0, 2, 4 and 6; at%) HEAs and concern their phase compositions, microstructures and wear properties. Hf leads to the formation of (Ni, Co) 2 Hf-type Laves phase and tailors the microstructure from a body-centered cubic (BCC) single-phase structure to a hypoeutectic structure. An increased hardness from ~ HV 512.3 to ~ HV 734.1 is due to solid-solution strengthening, grain refinement strengthening and precipitated phase strengthening. And a few oxides (Al 2 O 3  + Cr 2 O 3 ) caused by the wear heating contribute to an 85.5% decrease in wear rate of the HEA system from 6.71 × 10 −5 to 0.97 × 10 −5 m 3 ·N −1 ·m −1 . In addition, Hf addition changes the wear mechanism from abrasive wear, mild oxidative wear and adhesive wear to oxidative wear and adhesive wear.