热处理对一种新型增材制造镍基高温合金显微组织与拉伸性能的影响

本文研究了不同热处理工艺对一种新型增材制造镍基高温合金ZGH451组织性能的影响。结果表明，沉积态组织主要由外延生长的微细柱晶组成，枝晶间存在γ/γ＇共晶组织，合金中元素偏析造成了枝晶干与枝晶间处γ＇相尺寸差异，分别为100 nm和250 nm。不同热处理工艺合金的组织和性能存在一定差异：随着固溶温度由1180 ℃升高到1350 ℃，合金偏析程度逐渐减弱，直至1350 ℃发现初熔组织；随着一级时效温度由1050 ℃升高到1150 ℃，γ＇相的尺寸逐渐增大，形状由球状等不规则形状转变为立方状。综上，优化出适用于该合金的热处理工艺（HT2），与沉积态合金相比，完全热处理后合金的晶粒尺寸明显增大，且消除了合金的偏析及γ/γ＇共晶，在1000 ℃拉伸变形过程中γ/γ＇界面形成致密的位错网，抗拉强度和屈服强度分别为520 MPa和269 MPa，延伸率为11%。

Effect of heat treatment on microstructure and tensile properties of a new type of Ni-base superalloy designed for additive manufacturing

In this paper, the effects of different heat treatment processes on the microstructure and properties of a new type of Ni-based superalloy ZGH451 were studied. The results show that the as-deposited microstructure is mainly composed of epitaxial micro-columnar grains, and there is γ/γ＇ eutectic exists among the interdendritic region. The segregation of element in the alloy results in the size difference of γ＇ phase between dendritic region and interdendritic region, which are 100 nm and 250 nm, respectively. The microstructure and properties of alloy with varying heat treatment processes are different: as the solution temperature increases from 1180 ℃ to 1350 ℃, the segregation degree of the alloy decreases gradually until the initial melting microstructure is found at 1350 ℃. With the first aging temperature increasing from 1050 ℃ to 1150 ℃, the size of γ＇ phase increases gradually, and its shape changes from spherical and other irregular shape to cube shape. In summary, the heat treatment process (HT2) suitable for the alloy is optimized. Compared with the as-deposited alloy, the grain size of alloy is significantly increased after the complete heat treatment, and the segregation and γ/γ＇ eutectic of the alloy are eliminated. The denser dislocation network is formed at the γ/γ＇ interface during tensile deformation at 1000 ℃. The tensile strength and yield strength are 520 MPa and 269 MPa, respectively, and the elongation is 11%.