铜铝异种焊接用低温焊料Sn-40Bi-xZn的研究

Sn-40Bi-x Zn Low Temperature Solder for Cu-Al Dissimilar Welding

通过改变Sn-40Bi-xZn焊料合金中Zn元素含量,对比Sn-58Bi共晶焊料合金研究Zn含量对Sn-40Bi-xZn焊料合金的熔化过程、焊接润湿扩展性、微观组织结构、力学性能方面的影响.结果表明:随着Zn元素含量的增加,Sn-40Bi-xZn焊料合金熔点T变化不大,但熔程ΔT逐渐变小直至保持稳定;当Zn的质量分数含量为2.0%时,Sn-40Bi-xZn焊料合金的铺展率最大,焊料合金在Al板上的润湿效果最好;当Zn质量分数含量达到1.0%及以上时,Sn-40Bi-xZn/Cu界面层主要为Cu_(6)Sn_(5)和Cu_(5)Zn_(8)金属间化合物,且Cu_(6)Sn_(5)含量随着Zn的增加有降低趋势;在Sn-40Bi-xZn/Al界面处并无金属间化合物层形成,而是随着Zn元素的增加,富Zn相也增加,焊接界面逐渐形成富Bi相、Sn-Zn-Bi相、Al-Zn-Sn固溶体多相共存;随着Zn元素的增加,Sn-40Bi-xZn焊料合金应变率、铜铝焊接接头剪切强度均呈现上升趋势.

The article investigates the influence of zinc(Zn)content on the melting process,solder wettability and spreading,microstructure,and mechanical properties of Sn-40Bi-x Zn solder alloys by changing the Zn content in the Sn-40Bi-x Zn alloy and comparing it with Sn-58Bi eutectic solder alloy.The results indicate that with an increase in the Zn content,the melting point(T)of the Sn-40Bi-x Zn solder alloy remains relatively unchanged,but the melting range(ΔT)gradually decreases until it stabilizes.When the mass fraction of Zn is 2.0%,the spreading rate of the Sn-40Bi-x Zn solder alloy is maximized,and the wetting effect on an Al plate is optimal.At Zn mass fractions of 1.0%and above,the interface layer in Sn-40Bi-x Zn/Cu is primarily composed of Cu_(6)Sn_(5) and Cu_(5)Zn_(8) intermetallic compounds,with a decreasing trend in Cu_(6)Sn_(5) content as Zn increases.No intermetallic compound layer forms at the Sn-40Bi-x Zn/Al interface;instead,an increasing Zn element results in an enrichment of Zn phase,forming a coexistence of rich Bi phase,Sn-Zn-Bi phase,and Al-Zn-Sn solid solution at the welding interface.Simultaneously,an increase in Zn content leads to an upward trend in strain rate and shear strength of the copper-aluminum solder joints.