抽拉速率对SRR99单晶高温合金组织和性能的影响

Effects of withdrawal rate on microstructure and mechanical property of single crystal superalloy SRR99

用螺旋选晶法制备镍基单晶高温合金SRR99,研究了抽拉速率对其组织和性能的影响.随着抽拉速率的增大,SRR99单晶合金的铸态组织由粗枝状晶向细枝状晶演变,枝晶干与枝晶间的γ′相尺寸减小,且枝晶间γ′相的形状逐渐趋向于规则立方体形状,而γ-γ′共晶的含量增加.热处理后,在高抽拉速度下生成的共晶组织更容易固溶,形成更加均匀的组织.随着抽拉速率的增大,SRR99单晶合金的持久寿命延长.

The microstructure and mechanical property of single crystal superalloy SRR99 produced at different withdrawal rate were investigated. For the as-casting sample, the morphology of SRR99 alloy transforms from coarse dendrite to fine dendrite with the increase of withdrawal rate, the size of the γ＇particles decreases, the shape of γ＇ particles tends to be more regular, and the volume fraction of γ-γ＇eutectic increases. After heat treatment the γ-γ＇eutectic formed at the high withdrawal rate is much easier to solutionize so that more homogeneous microstructure can be obtained. The stress-rupture life of single crystal SRR99 is enhanced with the increasing of withdrawal rate.