采用选区激光熔化(SLM)成形方法, 对SRR99镍基高温合金进行了定向凝固实验, 测试了试样的显微组织、相组成及元素偏析情况。结果表明, 沉积层与铸态基板间能形成良好的冶金结合, 沉积试样组织由γ相和γ′相组成, 沉积层与铸态基板组织在衍射角为50.78°时均有一个最强衍射峰, 基板的生长取向在SLM沉积组织中得到了很好的延续, 且试样的一次枝晶间距仅为1~2 μm, 二次臂退化甚至消失。各合金元素的偏析比均接近1, 元素在枝晶间和枝晶干的分布较均匀。

The directional solidification experiment of SRR99 Ni-based superalloys is conducted by the selective laser melting (SLM) method, and the microstructure, the phase composition, the element segregation of samples are measured. The results show that a good metallurgical combination between the deposition layer and the as-cast substrate is formed, and the deposited samples are composed of the γ and γ′ phases. There is a strongest diffraction peak both in the deposition layer and the as-cast substrate when the diffraction angle is 50.78°, which indicates that the growth orientation of the substrate gets well extended in the SLM deposition structure. The primary dendrite spacing is only 1-2 μm and the secondary dendrite arm degenerates and even disappears. The segregation ratio of each alloy element is close to 1 and the elements are uniformly distributed at the dendrite arms and the interdendritic space.