定向凝固NiAl-28Cr-5.8Mo-0.2Hf合金的高温拉伸蠕变行为

TENSILE CREEP BEHAVIOR OF DIRECTIONALLY SOLIDIFIED NiAl-28Cr-5.8Mo-0.2Hf ALLOY

研究了定向凝固 ＮｉＡｌ－２８Ｃｒ－５．８Ｍｏ－０．２Ｈｆ合金的显微组织和在 ９８２—１１００℃、５０—１２４ ＭＰａ应力下的高温蠕变行为 该合金是由ＮｉＡｌ相．Ｃｒ（Ｍｏ）相和少量Ｈｆ的固溶体相组成．蠕变测试结果表明：蠕变曲线是由较短的减速蠕变阶段和较长的加速蠕变阶段组成，且蠕变后的显微组织变化不大，蠕变变形机制是由位错攀移机制所控制。加速蠕变阶段蠕变速率的增加是由于裂纹的形成与扩展引起的。

The microstructure and tensile creep behaviors of NiAl-28Cr-5.8Mo-0.2Hf alloy were studied at 982-1100 degreesC under the applied stress of 50 124 MPa. The alloy is composed of NiAl phase, Cr(Mo) phase and Hf-rich phase. The obtained creep curves have similar shape: a short primary creep and long accelerated creep stages. The post-creep microstructure is almost the same as the original microstructure. The dominant creep deformation mechanism is controlled by the climb of dislocations. The increase of creep rate at beginning of the accelerated creep stage is related to the nucleation and propagation of creep cracks.