大间隙钎焊用混合粉状高温镍基钎料的润湿性和显微组织

Wettability and Microstructures of High Temperature Ni-based Mixed Filler Powders for Wide Gap Brazing

用一种含Al,Ti元素的镍基钎料粉末与γ'相沉淀强化型镍基高温合金FGH95的粉末混合,制备了大间隙钎焊用混合粉状高温镍基钎料。实验表明,采用合适的混合比例,混合粉状钎料对1Cr18Ni9Ti不锈钢具有较好的润湿铺展性。该混合钎料所获得的钎缝金属的合金化效应显著,Al+Ti合金元素的最大含量达到了5.49%。焊态钎缝中,除Nb,W等个别元素外,其他主要强化元素无明显偏析,且经1180℃/4h扩散处理可消除合金元素的偏析。钎缝金属的组织状态较为均匀,基体为等轴γ固溶体枝晶,枝晶间分布有颗粒状、短条状的化合物相以及少量的γ+γ'共晶组织。另外,在γ固溶体中分布着大量弥散细小γ'沉淀强化相。

High temperature Ni-based mixed filler powders for wide gap brazing were produced by mixing a type of Ni-based high tem- perature filler powder containing aluminum and titanium and the γ′ precipitation strengthened Ni-based superalloy FGH95 powder. The experiment results indicate that the mixed powder filler metals with proper mixing ratio possess good wetting and spreading performances on the stainless steel 1Crl8Ni9Ti . Alloying effects in the brazing metal are considerable, and the maximum total content of aluminum and titanium elements is surprisingly up to 5.49%. The mixed brazing filler metals after high temperature brazing exhibit no remarkable element segregation except niobium and tungsten. After 1180℃/4b diffusion heat treatment, the element segregation is eliminated. The microstructures of the brazing metal are uniform comparatively ,and characterized by equiaxed 3,solid solution dendrites with interdendritic blocky and short-stripy compounds and a little γ ＋γ′eutectic , and especially a large amount of fine dispersed γ′precipitation hardening phases distribute in theγ solid solution, as expected.