新型Cr-Co-Mo-Ni合金的高温蠕变损伤

摘要：对500℃/950MPa条件下经845-8 h蠕变断裂的一种新型Cr-Co-Mo-Ni合金的蠕变损伤进行了分析，并且对蠕变孔洞的形成进行了研究。结果表明，蠕变断裂后，基体中呈链状分布的M6C相显著粗化，平均等效直径达到3.0μm，体积分数达到3.85%；马氏体板条上析出大量弥散细小的Laves相，尺寸在10～25nm之间，面积比达20%；蠕变孔洞在密集分布的链状M6C型析出相与基体结合界面上产生，其形成与M6C相的链状聚集和显著粗化有关；并且与高密度Laves相的析出有关；因此，控制链状M6C相的析出、聚集和长大能够提高该新型合金的抗高温蠕变性能。

High temperature creep damage behavior of a novel Co-Cr-Mo-Ni alloy

The creep damage behavior of a novel Cr Co Mo Ni alloy was investigated by conducting creep test at stress of 950MPa and temperature of 500℃ for 8458h, and the mechanism of creep damage was examined. The results showed that the chain like M6C phase distributed in the matrix coarsened seriously after creep rupture, and the mean diameter and volume fraction of M6C phase reached 30μm and 385%, respectively. A large amount of dispersed small Laves phases was precipitated among martensite lath after creep test, with a size between 10 and 25nm and an area fraction of 20%. The creep cavities were densely distributed at the interface of chain like M6C phase and matrix, and the formation of creep cavities was related to the chain aggregation and significant coarsening of M6C phase, as well as the precipitation of high density Laves phase. Therefore, the high temperature creep resistance of the novel alloy can be enhanced by controlling the precipitation, aggregation and growth of M6C phase.