利用FEG-SEM, TEM, AES和EDS分析技术以及物理化学相分析等方法, 系统地研究了微量元素Hf在镍基粉末高温合金中的作用. 结果表明: Hf以固溶态分布在枝晶间g固溶体内, 有助于减少原始粉末颗粒边界组织. Hf促进g′ 相形态失稳, 导致大尺寸立方状g′ 相发生分裂, 更快地进入g′ 相低能稳定的择优形态. Hf主要分布在g′ 相和MC型碳化物中, 改变g′ 相和MC型碳化物及g固溶体相间合金元素的再分配, 有利于消除合金的缺口敏感性, 改善合金综合力学性能.

Hafnium (Hf) is one of the most important microelements in powder metallurgy (P/M) superalloy. Hf modifies the microstructure and drastically improves mechanical properties in P/M superalloy. The effect of Hf in a nickel-based P/M superalloy was systematically studied by means of FEG-SEM, TEM, AES, EDS and physical and chemical phase analysis. Hf mainly distributes at interdendritic region of the solidification powder in form of solid solution, which is helpful to reduce prior particle boundary (PPB). Hf facilitates morphology of g′ phase to be unstable and enhances the large cubic g′ phase to split into smaller ones, so the g′ phase turns into a stable state with a lower energy faster. Hf is mainly distributed in g′ phase and MC carbides, which changes the distribution of element between the g′ phase, MC and g solid solution, which is beneficial to eliminate notch sensitivity and improves overall mechanical properties of the alloy.