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采用新型Ni-Co-Cr-W-B+DD99混合粉末钎料焊接DD5单晶高温合金,分析钎料成分对接头显微组织演变和接头力学性能的影响,探讨Ni-Co-Cr-W-B钎料/DD99合金粉的界面形成机制与接头形成机理.结果表明,在钎焊过程中,Ni-Co-CrW-B钎料/DD99合金粉的界面上首先形成了g-Ni初生相,B偏析并析出细小颗粒状的M3B2型硼化物,在冷却过程中残余液相形成块状M3B2相、g+g′共晶相和g-Ni+Ni3B+Cr B共晶相.提高混合粉末钎料中DD99合金粉的配比,可有效抑制焊缝中的硼化物和低熔点共晶相的形成,提高焊缝成分和组织均匀性.当DD99合金粉的配比增加至70%(质量分数)时,B可均匀扩散至DD5母材和DD99合金粉中,未观察到低熔点共晶相,界面处脆性化合物相显著减少,接头高温性能提高.接头经过固溶处理和时效处理后,在870℃的高温拉伸性能可提高至1010 MPa.
The effect of solder composition on the microstructure evolution and mechanical properties of the joint was analyzed by using a new type of Ni-Co-Cr-W-B + DD99 mixed powder solder to weld DD5 single crystal superalloy. The effects of Ni-Co-Cr-WB solder The formation mechanism and the mechanism of the formation of the interface between the DD99 alloy powder and the filler / DD99 alloy powder were investigated. The results show that the g-Ni primary phase and the B segregation are formed at the interface of the Ni-Co-CrW-B filler / DD99 alloy powder during the brazing process And the precipitated fine grained M3B2 boride, the residual liquid phase during cooling formed massive M3B2 phase, g + g ’eutectic phase and g-Ni + Ni3B + Cr B eutectic phase to improve the mixed powder solder DD99 alloy powder can effectively restrain the formation of borides and low-melting eutectic phase in the weld and improve the composition and uniformity of the weld.When the proportion of DD99 alloy powder is increased to 70% (mass fraction) , B can be uniformly dispersed into the DD5 base metal and DD99 alloy powder, no low-melting eutectic phase was observed, the interface of brittle compounds significantly reduced, high-temperature performance joints increased after solution treatment and aging treatment joint, at 870 ℃ The high temperature tensile properties can be increased to 1010 MPa.