Microstructure and mechanical properties of (Mg, Ce)-modified Al-7.5Si-15Cu-5Zn brazing joints on 5083 aluminum alloy

This study investigated the microstructural evolution of Al-7.5Si-15Cu-5Zn brazing alloys modified by adding 0.5 wt.% Mg and xCe (x = 0.05, 0.1, 0.2, 0.3, 0.4 wt.%) . The mechanical properties of the corresponding brazing joints on 5083 aluminum alloy were measured with the aid of first-principle calculations. Results show that Mg and Ce elements refine the microstructure of Al-7.5Si-15Cu-5Zn brazing alloys by changing the morphology of the intermetallic phases. There is an interface zone between the brazing alloy and the base alloy in the joints and the thickness of interface zone evolves with the Mg addition and Ce contents. The virtual crystal approximation (VCA) method predicts the best mechanical properties of the joints using Al-7.5Si-15Cu-5Zn-0.5 Mg-0.2Ce brazing alloy, exhibiting the measured tensile strength, elongation and microhardness of 261.14 MPa, 11.95% and 194.6 HV0.2, respectively. Compared to the base brazing alloy without Mg and Ce additions, the tensile strength is increased by 42% and the elongation is improved by 47%.