铱合金的高温氧化行为  

Oxidating behavior of iridium alloys at high temperature

作　　者：李增峰[1] 张晗亮[1] 汤慧萍[1] 向长淑[1] 黄愿平[1] 李爱君[1] 刘海彦[1] 石英[1] 

机构地区：[1]西北有色金属研究院金属多孔材料国家重点实验室,陕西西安710016

出　　处：《金属热处理》2012年第10期12-16,共5页Heat Treatment of Metals

基　　金：国家自然科学基金(50801053);西部之光项目

摘　　要：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。Iridium alloys with typical contents of Ir-W-Th and Ir-W-La were adopted to investigate the oxidating behavior at 500,800, 1200℃ for 25, 50, 75 and 100 h in atmosphere, respectively in order to evaluate the resist-oxidation of the alloys. The experiments were held at different temperatures and time, the quality changes and the structure of the samples were analyzed. The experiments show that during the course of calcinations at high temperature, W, Mo, Th, La and other impurities which enriched in crystal boundary areas are oxidated rapidly at the first stage. Subsequently, the oxidation occurs from the impurities at crystal boundary and inter-crystals with the weights increased of the samples. Whereas, with the increasing of the temperature and prolonged calcinations time, the volatilization increases, and the samples lighten at the same time. The microstructure shows that with the temperature increasing and prolonged calcinations time, the crystal boundary of the two kinds of Ir alloys become narrow and grains coarse. Meanwhile, W, Mo, Th, La and other impurities which anchored in the crystal boundary and inter-grains of the alloys are decreased or disappeared. Experimental results show that the weights changes of the two kinds of Ir alloys are very little after calcinations under the temperature of 1200 ℃ in atmosphere, both are as less as 1 mg · cm-2 . h-1. The oxidation loss is primarily from W, Mo, Th, La and other impurities of the Ir alloys, the base element Ir changes very little.

关 键 词：铱合金 煅烧 高温氧化 氧化速率 挥发速率 显微组织 

分 类 号：TQ028.8[化学工程]