中文摘要：

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1~2μm,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。

英文摘要：

The directional solidification experiment of SRR99 Ni-based superalloys is conducted by the selective laser melting （SLM） method, and the microstrueture, 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 1-2μm 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.