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添加铪是改善合金中温性能的有效途径之一。本文在R合金基础上研究了加铪后合金中显微组织和相组成发生的明显变化。合金中约有90％的铪溶入γ′相中,其余溶入碳化物及形成少量的Ni_5Hf相,而在基体中溶入甚微。铪大量进入γ′中,使γ′〔(包括共晶(γ+γ′)〕数量增加,从未加铪的R合金的62wt％,增至加铪的R_H合金的64wt％,提高了γ′固溶温度约40℃,高温显微硬度明显的高于不加铪的R合金。由于铪富集于枝晶间,使共晶(γ+γ′)数量从R合金的8vol％增至R_H的18vol％,所以γ′数量的增加实际上是共晶(γ+γ′)数量的增加。铪的加入使MC和M_3B_2,形态从“草书体”或骨架状向块状或条状转变;降低了固液相线,扩大了两相区约10℃。
Adding hafnium is one of the effective ways to improve the temperature performance of the alloy. In this paper, based on the R alloy, the microstructure and phase composition of the hafnium-added alloy were studied. About 90% of the alloy hafnium dissolved into the γ ’phase, the rest dissolved into the carbide and the formation of a small amount of Ni_5Hf phase, and little into the matrix. The amount of γ ’[(including eutectic (γ + γ’)] increased from 62% by weight of the hafnium-free R alloy to 64% by weight of the hafnium-added R_H alloy, thereby increasing γ ’Solution temperature of about 40 ° C, high temperature microhardness was significantly higher than the hafnium-free R alloy due to hafnium enrichment in the interdendritic, eutectic (γ + γ’) the number of R from 8vol% R_H 18vol%, so the increase in the number of γ ’is actually an increase in the number of eutectic (γ + γ’). The addition of hafnium so that MC and M_3B_2, morphology from the “cursive” or skeleton-like block or strip transition ; Reducing the solid-liquid line, expanding the two-phase zone about 10 ℃.