一、引言在耐热金属材料中,微量稀土金属添加剂最突出的作用在于改善材料的抗氧化性。早在四十年代初已利用稀土的这种作用来改善电热合金的性能。稀土在耐热钢和高温合金中的应用始于五十年代,当时只是为了改善热加工性、热塑性和热强性。稀土对它们抗氧化性的影响在六十年代以后得到了重视,近十几年的研究更加活跃。产生这一变化的主要原因是飞机发动机工作温度逐年提高(每年约提高20℃, I. Introduction In the heat-resistant metal materials, the most prominent role of trace rare earth metal additives is to improve the oxidation resistance of the material. As early as the early 1940s, this role of rare earths has been exploited to improve the performance of electric heating alloys. The use of rare earths in heat-resistant steels and superalloys began in the 1950s with the sole aim of improving hot workability, thermoplastics and hot strength. The influence of rare earth on their antioxidation has been paid more attention since the 1960s, and the research of the past ten years has been more active. The main reason for this change is that the working temperature of the aircraft engine is increasing year by year (about 20 ° C per year,