新型高温合金热处理及长期时效过程中组织稳定性研究

Research on the Stability of Microstructure of New Nickel-Based Superalloys During Heat-Treatment and Long-Time Aging

主要研究了三种新型高温合金在铸态热处理后,再经750℃/2 700 h和850℃/2 700 h长时间时效后的组织稳定性。结合相图计算探讨了不同合金设计对长期时效过程中针状组织演变规律的影响。结果表明:Nb+Ti+Ta总含量对铸态偏析组织及其后热处理及时效过程中的析出相演变具有重要影响,高Nb+Ti+Ta含量合金拥有较高的共晶体积分数,并易于在其附近形成不稳定的η相;随时效时间延长和温度升高,共晶体积分数减少,η相的体积分数降低,在组织中逐渐析出更为平衡的TCP相。

The purpose of this paper is to research the stability of three new heat-treated nickel based superalloys during long time aging at 750 ℃/2 700 h and 850 ℃/2 700 h. With the phase calculation, the influence of different alloy designs on the evolution of needle-like phase in long time aging process is discussed. The results show that the total content of Nb＋Ti＋Ta has an important influence on the precipitation of needle-like phases of the superalloy after heat treatment and during long time aging at high temperatures; higher content of Nb＋Ti＋Ta results in higher eutectic percentage during solidification, and gives rise to an inclination for the formation of η phase; long time aging at high temperatures decrease the eutectic and alleviate the η phase consequently, while the balanced TCP phase emerged gradually.