760℃时效组织稳定性
(1. 北京科技大学 高温合金研究室, 北京 100083；
2. 宁夏大学 物理系, 银川 750021)
摘 要: 利用热力学计算、 SEM、 TEM和相分析研究了一种新型Ni-Cr-Co基高温合金在704℃和760℃长期时效至2000h后的组织变化。 结果表明： 该合金标准热处理态和在704℃长期时效后的析出相有MC, M23C6, M6C和γ′， 在760℃长期时效后还析出了η相。 随时效时间增加， γ′(+η)及碳化物MC, M23C6和M6C的含量变化很小， 化学组成稳定，但γ′相粗化明显。 该合金在760℃时效时， η相的析出随时效时间的增加而加剧， 并且呈魏氏体分布。新合金在704℃长期时效时具有良好的组织稳定性，但在760℃时效时组织稳定性较差。
关键字: Ni-Cr-Co基高温合金； 热力学计算； 组织稳定性； 析出相
（1. High Temperature Materials Research Laboratory,
University of Science and Technology Beijing,Beijing 100083, China;
2. Department of Physics, Ningxia University,Yinchuan 750021, China）
Abstract:Thermodynamic calculation, SEM, TEM, XRD, phase extraction and chemical analysis were employed to study the structure stability of a new Ni-Cr-Co base superalloy aged at 704℃ and 760℃ for long time. The results show that the precipitates of alloy standard heat-treated and heat-treated at 704℃ and 760℃ for time up to 2000h are γ′, MC, M23C6 and M6C, and η phases are also formed at grain boundaries and in the matrix of sample heat-treated at 760℃ as well. With increase in aging time, the mass fractions of γ′(+η), MC, M23C6 and M6C in all samples have no large changes and their chemical compositions are stable at the same temperature, but the γ′ precipitates grow obviously. The γ′-to-η transformation in sample heat-treated at 760℃ takes place with prolonged aging time. Theη precipitates form a Widmansttten pattern in samples heat-treated at 760℃. The new alloy maintains a better structure stability during prolonged aging at 704℃, but a worse structure stability during prolonged aging at 760℃.
Key words: Ni-Cr-Co base superalloy; thermodynamic calculation; structure stability; preci
