应力对DD5单晶高温合金持久过程中析出相的影响

Effect of stress on precipitated phases in DD5 single crystal superalloy during stress rupture tests

利用扫描电镜和透射电镜研究了DD5单晶高温合金在持久性能测试过程中试样不同位置析出相的析出规律,分析了应力对析出相析出行为的影响并鉴定了两种析出相的种类。研究结果表明该合金在1 038℃/172MPa条件下随着局部拉应力的增大,枝晶间和枝晶干析出相数量都明显增加;合金在871℃/552 MPa条件下只在枝晶间区域析出少量粒状析出相,且随拉应力的增大,析出相数量有所增加;透射电镜分析表明合金的枝晶干区域的析出相主要为μ相,枝晶间析出粒状析出相主要为M23C6碳化物相。

The precipitation of second phase particles at different sites of the specimen in DD5 single crystal superalloy during stress rupture tests is investigated using a scanning electron microscope and a transmission electron microscope.Effect of stress on the precipitation of the second phases and the crystal structure of the two precipitated phases are analysed.The results show that at 1 038 ℃/172 MPa,with the increase of the local tensile stress,the number of precipitated phases in both the interdendritic region and the dendrite arm increases obviously,whereas at 871℃/552 MPa,only a small number of granular precipitates are precipitated in the interdendritic region,and the number of precipitates increases with the increase of the tensile stress.The TEM analysis shows that the phase precipitated in the dendrite arm is mainlyμphase with a rhombohedral structure and that precipitated in the interdendritic region is mainly M23 C6 phase.