含镍中间层铍青铜微电阻点焊接头形成机理

采用微电阻点焊对0.1 mm厚铍青铜薄片加入0.05 mm的镍中间层进行了搭接点焊，通过拉剪试验、光学显微镜、扫描电镜和能谱分析，研究了镍中间层对超薄铍青铜微电阻点焊接头形成过程和接头强度的影响. 结果表明，含镍中间层的超薄铍青铜微电阻点焊接头主要包括钎焊连接和熔化-钎焊混合连接机制. 其形成过程会经历铜合金润湿铺展、元素扩散、镍铜界面反应和金属凝固四个过程. 在这两种接头中，钎焊连接接头断裂方式为沿结合面断裂，熔化-钎焊连接接头断裂方式为纽扣断裂，断口都呈现韧性断裂与脆性断裂混合特征.

Formation mechanism of micro-resistance spot welded joints of QBe2 with Ni interlayer

Lap welding of 0.1 mm-thick beryllium bronze with nickel interlayer was realized using micro-resistance spot welding. Tensile shear test, optical microscopy (OM) scan electric microscopy (SEM) and energy spectrum analysis (EDS) were used to study the influence of Ni interlayer on the dissimilar joint formation and the joints’ shear strength. The results show that, mechanism of beryllium bronze with nickel interlayer joint formation were solder bonding and fusion-solder bonding; The formation of the joint has gone through four processes: copper alloy wetting and spreading, element diffusion, nickel-copper interface reaction and metal solidification. Under the two kinds of joint formation mechanism, the fracture mechanism of solder bonding is fracturing along the interface, and it’s button fracture when fusion-solder welding. Their fractures present ductile fracture with a mixed characteristic of brittle fracture.