(1. 辽宁工业大学 材料科学与工程学院，锦州 121001；
2. 中国科学院 金属研究所，沈阳 110016)
摘 要: 采用SEM和TEM分析蠕变前、后的显微组织，研究定向凝固NiAl-Cr(Mo)-W/Nb合金在1 223~1 373 K温度区间的拉伸蠕变行为的机理。结果表明：定向凝固NiAl-Cr(Mo)-W/Nb合金的横向显微组织为典型的胞状共晶，纵向显微组织具有明显的方向性，Cr(Mo)相以片层状沿凝固方向分布。在所采用的温度和外加应力条件下，合金蠕变曲线均具有较短的减速蠕变阶段和相当长的稳态蠕变阶段及较高的蠕变应变，蠕变应变范围为15%~28%。蠕变过程发生动态回复和动态再结晶，蠕变过程是由扩散和位错蠕变共同控制。合金蠕变断裂主要受蠕变裂纹的形成与扩展的控制，蠕变断裂的方式为沿相界的剥离。
关键字: NiAl基合金；定向凝固；蠕变；蠕变断裂
NiAl-Cr(Mo)-W/Nb alloy
（1. School of Materials Science and Engineering, Liaoning University of Technology, Jinzhou 121001, China;
2. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:The microstructures before and after creep were also analyzed by SEM and TEM. The tensile creep behavior and mechanisms of directionally solidified (DS) NiAl-Cr(Mo)-W/Nb alloy were investigated in the temperature range of 1 223−1 373 K. The results show that the transverse microstructure of DS NiAl-Cr(Mo)-W/Nb alloy is typically eutectic cell of NiAl matrix and Cr(Mo) phase. The lamellar Cr(Mo) phase of the longitudinal microstructure is arranged along the direction of the directional solidification. At the present experiment, all of the creep curves of DS NiAl-Cr(Mo)-W/Nb alloy have the similar shape, i.e. shorter primary creep, longer steady state creep stage and higher creep strain. The creep strains are 15%−28%. The creep deformation mechanism is probably controlled by high temperature diffusion and dislocation creep. The creep fracture of this alloy is controlled by formation and propagation of the cracks at the phase boundaries, and the creep fracture mode is debonding along the phase boundary.
Key words: NiAl-based alloy; directional solidification; creep; creep rupture
