Influence of alloy elements on microstructure and mechanical properties of Al/steel dissimilar joint by laser welding/brazing

The problem in dissimilar material joining (e.g., Al/steel) is the degradation of joint mechanical properties by formation of the hard and brittle interfacial intermetallic compounds. In the present study, in order to improve the joint mechanical properties, alloy elements Si and Zn are added in the form of Al-Si and Zn-Al filler metals, respectively. The effects of alloy elements on the joints are investigated in terms of interfacial microstructure and mechanical properties. The results have shown that element Si is able to suppress the growth of interfacial reaction layer, which leads to the improvement in the fracture load, while element Zn is capable of reducing the brittleness of reaction layer, and it consequently enhances the fracture load.