一种定向凝固镍基高温合金950℃长期时效1000h的组织演变(英文)

Microstructure evolution of a new directionally solidified Ni-based superalloy after long-term aging at 950 ℃ upto 1 000 h

研究一种用于燃气轮机叶片的定向凝固镍基高温合金在950℃长期时效1000后的组织演变。结果表明:随着时效时间的延长,在枝晶和枝晶间的γ'相变得更加有规则,而且γ'相的质量分数和尺寸也随着时效时间的延长而逐渐增加。在时效过程中,MC型碳化物的边缘部分发生溶解,而由其提供的碳元素与析出的Cr元素在晶界处形成M23C6型碳化物。玫瑰状的γ′/γ共晶部分溶解进入基体,时效过程也促进其向筏形γ′转变。合金经过1000h时效后,结构总体上是稳定的,没有发现针状的TCP相。

The microstructure evolution of a new directionally solidified（DS） Ni-based superalloy used for gas turbine blades after long-term aging at 950 ℃ was investigated.The results show that the γ ＇ phase becomes more regular in dendritic arm and interdendritic area,while both the mass fraction and the size of γ ＇ phase increase gradually with increasing aging time.During long-term aging,the MC carbide dissolves on the edge to provide the carbon for the formation of M23C6 carbide by the precipitation of Cr at the grain boundary.The rose-shaped γ ＇/γ eutectic partly dissolves into γ matrix and the aging promotes it transform into raft-shape γ ＇.The microstructure is generally stable and no needle-like topologically close-packed phase（TCP） can be found after aging for 1 000 h.