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选用新研制的高温铱合金Ir-W-Th和Ir-W-La,在大气中于500、800、1200℃分别煅烧25、50、75、100 h,分析其氧化行为,以此评价Ir合金的高温抗氧化性能。通过不同温度、时间的煅烧试验,对样品质量变化及组织进行分析。试验发现两种铱合金在高温煅烧时,晶界中富集的W、Mo、Th、La及杂质首先快速氧化,随后扩展为铱晶界及晶间杂质氧化,质量增加。但随着温度的升高和时间的延长,挥发量增大,样品质量减小。显微组织观察显示,随着煅烧温度的升高和时间的延长,两种铱合金的晶界变细变少,晶粒变大,晶界及晶间钉扎的W、Mo、Th、La及杂质也减少或消失。结果表明,两种铱合金在大气中1200℃以下高温煅烧后质量变化很小,均小于1 mg.cm-2.h-1。氧化损失主要是铱合金中的W、Mo、La、Th及杂质,基体元素铱的变化很小。
The newly developed high-temperature Ir-W-Th and Ir-W-La alloys were calcined in the air at 500, 800 and 1200 ℃ for 25, 50, 75 and 100 h, respectively. The oxidation behavior of Ir alloy High temperature oxidation resistance. Through the calcination test with different temperature and time, the change of the sample quality and the organization were analyzed. It is found that W, Mo, Th, La and impurities enriched in the grain boundary are rapidly oxidized firstly and then expand into the iridium grain boundaries and the intergranular impurities are oxidized and their mass increases when the two iridium alloys are calcined at high temperature. However, with the increase of temperature and time, the amount of volatilization increases and the sample quality decreases. Microstructure observation showed that with the increase of calcination temperature and the extension of time, the grain boundaries of the two iridium alloys became smaller and smaller, the grains became larger, and the grain boundaries and inter-grain pinning of W, Mo, Th, La And impurities also reduce or disappear. The results show that the mass changes of the two iridium alloys after calcination at 1200 ℃ in the atmosphere are all very small, all less than 1 mg.cm-2.h-1. The oxidation loss is mainly W, Mo, La, Th and impurities in the iridium alloy, and the change of the matrix element iridium is small.