凝固速率及铼对镍基单晶高温合金叶片小角度晶界的影响

Effect of Solidification Rate and Rhenium on Low Angle Boundaries of Nickel Base Single Crystal Superalloy Blades

利用高速凝固(HRS)技术制备了不同成分单晶模拟叶片铸件,分析了截面渐变过渡区和截面突变平台处的组织特征。结果表明:在过渡区,枝晶排列由中心向边缘靠近,取向偏离有累加的趋势;在抽拉速率75、100、150μm/s下,试样平台处均出现了小角度晶界,晶界角度在75μm/s下最大,为6.8°;对不同含Re试样分析表明:随着Re含量的增加,平台处晶界角度增大。

The single crystal blade simulative castings of different components were prepared by using high rate solidification （HRS） method. Microstructure characteristics of tapered transition zone and abrupt change of cross-section platform were analyzed. The results show that orientation deviation of dendritic arrangement from center to edge at transition zone has cumulative tendency. There are low angle boundaries at platform ofaU samples under withdrawal rate of 75, 100 and 150 μm/s, and the boundary angle reaches 6.8°at withdrawal rate of 75 μm/s, which is maximum. The analysis of different samples containing Re shows that boundary angle increases at platform with rhenium content increasing.