Mukanov Samat, Loginov Pavel, Fedotov Alexander, Bychkova Marina, Antonyuk Maria, Levashov Evgeny
Department of Powder Metallurgy and Functional Coatings, National University of Science and Technology «MISIS», Leninskiy Prospekt 4, 119049 Moscow, Russia.
Materials (Basel). 2023 Jan 30;16(3):1178. doi: 10.3390/ma16031178.
This paper focuses on the microstructure, phase composition, mechanical, tribological and corrosion properties of high-entropy alloys (HEAs) in the CoCrCuFeNi system depending on copper content, which was varied from 0 to 20 at. % with an increment of 5%. CoCrCuFeNi alloys were manufactured by powder metallurgy methods: mechanical alloying and hot pressing of element mixtures. The solubility limit of copper in CoCrFeNi solid solution was found to be 9 at. %. Segregation of irregularly shaped copper grains sized 1-30 μm is observed at concentrations above this solubility limit. As copper concentration increases, the phase composition of CoCrCuFeNi alloys changes from the single phase based on FCC1 solid solution (Cu = 0-5 at. %) to the dual-phase FCC1 + FCC2 alloy (Cu = 10-20 at. %), where FCC1 is the main phase and FCC2 is the secondary copper-rich phase. Tribological tests have shown that doping the CoCrFeNi alloy with copper increased wear resistance by 23% due to solid solution hardening. As copper content rises above 20%, the content of the secondary FCC2 phase increases, while wear resistance and alloy hardness decline. An analysis of wear tracks and wear products has shown that abrasion of CoCrCuFeNi alloys occurs via the abrasive-oxidative wear mechanism. The corrosion tests of CoCrCuFeNi HEAs in 3.5% NaCl solution had demonstrated that doping the alloy with copper at low concentrations (5-10%) leads to decreasing of corrosion resistance, possibly due to the formation of undesirable oxide CuO along with protective CrO. At high copper concentrations (15-20%) galvanic corrosion is suppressed due to coarsening of FCC2 grains and thus decreasing the specific contact surface area between the cathode (FCC2) and the anode (FCC1).
本文聚焦于CoCrCuFeNi体系中高熵合金（HEA）的微观结构、相组成、力学性能、摩擦学性能和腐蚀性能，这些性能取决于铜含量，铜含量在0至20原子百分比之间变化，增量为5%。CoCrCuFeNi合金通过粉末冶金方法制造：对元素混合物进行机械合金化和热压。发现铜在CoCrFeNi固溶体中的溶解度极限为9原子百分比。在高于此溶解度极限的浓度下，观察到尺寸为1 - 30μm的不规则形状铜晶粒的偏析。随着铜浓度增加，CoCrCuFeNi合金的相组成从基于FCC1固溶体的单相（Cu = 0 - 5原子百分比）变为双相FCC1 + FCC2合金（Cu = 10 - 20原子百分比），其中FCC1是主相，FCC2是富铜第二相。摩擦学测试表明，由于固溶强化，用铜掺杂CoCrFeNi合金可使耐磨性提高23%。当铜含量超过20%时，第二相FCC2的含量增加，而耐磨性和合金硬度下降。对磨损轨迹和磨损产物的分析表明，CoCrCuFeNi合金的磨损通过磨料 - 氧化磨损机制发生。CoCrCuFeNi高熵合金在3.5% NaCl溶液中的腐蚀测试表明，在低浓度（5 - 10%）下用铜掺杂合金会导致耐腐蚀性降低，这可能是由于形成了不良氧化物CuO以及保护性的CrO。在高铜浓度（15 - 20%）下，由于FCC2晶粒粗化，从而减小了阴极（FCC2）和阳极（FCC1）之间的比接触表面积，电偶腐蚀受到抑制。
