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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。
The high-temperature AlCoCrFeNiTi_ (0.5) multi-host high-entropy alloys were prepared by vacuum induction suspension melting in a water-cooled copper crucible. The oxidation behavior of the alloys at 800, 900, 1000 and 1100 ℃ were investigated. Morphology was analyzed to explore the oxidation mechanism of the alloy. The results show that the oxidation kinetics curves of the alloys approximate the sixth-order parabolic law at 800 and 900 ℃, and follow the fourth-order parabolic law approximately at 1000 and 1100 ℃. The alloys have excellent oxidation resistance, antioxidant levels at 800, 900 and 1100 ° C, and full oxidation levels at 1000 ° C. Oxidation of the alloy occurs mainly in dendrites and eutectic zones, and was aggregated into island-like aggregates. The oxide of the alloy peeled off obviously at 1100 ℃ and the main oxidation products were TiO_2, Fe_2TiO_5 and FeCr_2O_4. The dendrite phase The oxidation products were single, Al_2O_3 particles dispersed at 1000 ℃ and below, and were dense Al_2O_3 at 1100 ℃. After high temperature oxidation, the alloy matrix phase structure is stable, no softening phenomenon.