Ti/Al比对镍基单晶高温合金组织和持久性能的影响

Effect of Ti/Al Ratio on the Microstructure and Stress Rupture Property in a Ni-Base Single Crystal Superalloy

摘要:

研究了Al+Ti原子总量相同、Ti/Al比不同的3种单晶高温合金的微观组织和持久性能，讨论了无Re单晶高温合金中Al和Ti元素的成分设计原则。利用金相显微镜和扫描电镜对铸态和热处理态组织进行观察和分析；利用透射电镜的EDS对合金元素在两相中的分配比和错配度进行测试和分析。结果表明：随着Ti/Al比的增加，合金铸态枝晶间的g ￠-g共晶含量略有增加；热处理态g ￠相尺寸略有降低，g ￠相形貌逐渐规则，错配度略有降低。Ti/Al比的变化对合金的相变温度影响不大。Ti/Al比的变化对合金元素在两相中的分配有明显的影响，高Ti/Al比使合金元素在g ￠和g中的分配比更偏离于1。随着Ti/Al比的增加，合金的持久寿命逐渐增加。

Abstract:

The microstructure and stress rupture properties of three experimental single crystal nickel superalloys with different Ti/Al ratios were investigated. The microstructure as-cast state and after heat treatment was analyzed by OPM and SEM. Partition ratio of alloy element in two phase and misfit degree were measured and analyzed by TEM with EDS. The results show that with increasing of Ti/Al ratio, the amount of g-g ￠ eutectic in interdendrtic region as-cast state increases slightly, the size of g ￠ phase in heat treated state decreases a little and the morphology turns regular and the misfit decreases. The change of Ti/Al ratio has no obvious effect on the transformation temperatures. The stress rupture life is improved gradually with increasing of Ti/Al ratio.