AlCoCrFeNiTi_(0.5)高熵合金的高温氧化行为

采用水冷铜坩埚真空感应悬浮熔炼法制备AlCoCrFeNiTi_(0.5)多主元高熵合金,研究合金在800、900、1000和1100℃下的高温氧化行为,采用XRD,SEM及EDS对氧化膜的成分及形貌进行了分析,探索了合金的氧化机制。结果表明,合金的氧化动力学曲线在800和900℃时近似遵循六次方抛物线规律,在1000和1100℃时近似遵循四次方抛物线规律。合金具有优异的抗氧化性,在800、900和1100℃下为抗氧化级别,而在1000℃下为完全抗氧化级别。合金的氧化主要发生在枝晶间和共晶区,呈岛状团聚堆叠生长,1100℃氧化时该区域的氧化物发生明显剥落,氧化产物主要是TiO_2、Fe_2TiO_5和FeCr_2O_4等;而枝晶相的氧化产物较单一,1000℃及以下温度氧化时为弥散分布的Al_2O_3颗粒,1100℃氧化时为致密的Al_2O_3氧化层。高温氧化后,合金基体相结构稳定,未出现软化现象。

Oxidation Behavior of AlCoCrFeNiTi0.5 High-Entropy Alloy at High Temperature

AlCoCrFeNiTi0.5 high-entropy alloy was prepared by water cooled copper crucible vacuum induction levitation melting, and then the oxidation behavior of the alloy was studied at 800, 900, 1000 and 1100 °C. The ingredients and morphology of oxide films were analyzed by XRD, SEM and EDS, and the oxidation mechanism of the alloy was explored. The results show that the oxidation kinetics curve of the alloy obeys six power of parabolic law at 800 and 900 °C, while it follows the quadruplicate parabolic law at 1000 and 1100 °C. The alloy exhibits excellent oxidation resistance and it is of antioxidant level at 800, 900 and 1100 °C and completely of antioxidant level at 1000 °C. Oxidation occurs mainly in interdendritic and eutectic area, and the oxidation products are mainly TiO2, Fe2TiO5 and FeCr2O4, reuniting in an island morphology, which flake remarkably at 1100 °C. While the oxidation products in dendritic area are simple, which are diffusely distributed Al2O3 particles below 1000 °C, and dense Al2O3 layer at 1100 °C. Both phase structure and hardness of the alloy are stable after high-temperature oxidation