The oxidation behavior of Cu-20Co-20Cr alloy prepared by mechanically alloying(MA) was studied at 800 ℃ in 0.1 MPa pure O2.The alloy is composed of a mixture of two phases, α phase with the largest Cu form the matrix, while βphase with the largest Cr presented in the form of nets.The oxidation kinetics curve deviates from the parabolic rate law, and the instant parabolic rate constant increases with time more rapidly than required by the parabolic rate law.The alloy formed a multi-layer oxide scale structure, where the external layer is composed of CuO, while internal layer is mainly composed of Co2O3 and Cu2O with some black island spinel oxides of Cu2Cr2O4 and Co2Cr2O6.Moreover, the content of Cr in scales increases gradually from the external layer to internal layer, but the alloy is unable to form a continuous and thin Cr2O2 oxide layer on the surface finally.The oxidation rate of MACu-20Co-20Cr alloy was significantly higher than PMCu-20Co-20Cr alloy.This shows Cu-20Co-20Cr alloy that the rate of diffusion was greatly accelerated among different elements was unable to form the selective external oxidation of reactive component Cr after the grain size is refined.%研究了机械合金化(MA)制备的Cu-20Co-20Cr合金在800℃,0.1 MPa纯氧气中的氧化行为.结果表明合金由两相组成,合金基体为富Cu的α相,富Cr的β相则以网状形式分散在α相中.合金的氧化动力学曲线不规则且偏离抛物线规律,其瞬时抛物线速率常数随时间而升高.合金表面形成的氧化膜为最多层结构,外层是一连续的CuO层,相邻的内层是以Co2O3,Cu2O为主及岛状黑色尖晶氧化物Cu2Cr2O4和Co2Cr2O6组成的混合氧化区,且越靠近合金内部氧化物的Cr含量越高,但最终未能形成连续的Cr2O3外氧化膜.MACu-20Co-20Cr合金的氧化速率明显高于PMCu-20Co-20Cr合金.可见,晶粒尺寸降低后Cu-20Co-20Cr合金组元间的扩散速度大大加快了,但其表面未能发生活泼组元Cr的选择性外氧化.
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