镍基单晶高温合金研究进展

Research Progress of Nickel-Base Single Crystal Superalloys

单晶高温合金因具有较高的高温强度、优异的蠕变与疲劳抗力以及良好的抗氧化性、抗热腐蚀性、组织稳定性和使用可靠性,广泛应用于涡轮发动机等先进动力推进系统涡轮叶片等部件。由于采用定向凝固工艺消除了晶界,单晶高温合金明显减少了降低熔点的晶界强化元素,提高了合金的初熔温度,能够在较高温度范围进行固溶和时效处理,其高温强度比等轴晶和定向柱晶高温合金也大幅度提高。经过几十年的发展,单晶高温合金已经在合金设计方法、组织结构与力学性能关系、纯净化冶炼工艺和定向凝固工艺等方面取得了重要进展。从单晶高温合金成分特点、合金元素作用、强化机理、力学性能各向异性、凝固过程及缺陷控制、单晶制备工艺等方面,简要介绍了单晶高温合金的主要研究进展。

Single crystal superalloys have been widely used to make turbine blades and guide vanes for aeroengines and industrial gas turbines because of improved strength, creeprupture, fatigue, oxidation and hot corrosion properties as well as stable microstructure and reliability at high temperature environments. After removal of grain boundary by using directional solidification technique, grain boundary elements that decrease the incipient melting temperature were reduced remarkably in single crystal superalloys. Consequently, the solution and aging treatment of single crystal superalloys can be done at higher temperature due to the enhanced incipient melting temperature, and then the high temperature strength of single crystal superalloys is higher than that of equiaxed and directionally solidified superalloys. There were great progresses on approach of alloy design, relationship between structure and mechanical performances, process of pure smelting and directional solidification in the last decades. The present work reviews these progresses from compositions of alloys, role of elements, mechanism of strengthening, anisotropy of mechanical properties, procedure of solidification, control of defects and processing of single crystal superalloys.