Microstructure and shear strength of vacuum contact reactive brazed joints of 6A02 aluminum alloy

Vacuum contact reactive brazing was used to carry out connection test of 6A02 aluminum alloy with T2 copper foil as interlayer. Analysis method of SEM, energy spectrum and strength were adopted to analyze influence of brazing parameters on microstructure and mechanical properties of brazed joints. The results showed that when copper foil vacuum contact reactive brazing of 6A02 aluminum alloy was used, corrosion defects were easy to appear on both sides of brazed joints. Moreover, the higher connection temperature was and the longer holding time was, the more serious dissolution degree was. Common defects such as porosity and slag inclusion were not found in brazed joints, and dense brazed joints could be obtained by contact reactive brazing. When joining temperature was 560 ℃, microstructure of brazed joints consisted of 6A02 aluminum alloy, α-Al solid solution, CuAl₂ and Mg₂Si. When joining temperature was 570 ℃ and 580 ℃, short rod-shaped ω-FeCu₂Al₇ microstructure appeared in brazed joints, and microstructure appeared in brazed joints was 6A02 alloy, α-Al solid solution, CuAl₂, Mg₂Si and ω-FeCu₂Al₇. When joining temperature 570 ℃ and holding time was 30 min, the maximum shear strength of brazed joints was 38.5 MPa, and fracture was located in the brittle CuAl₂ reaction layer of 6A02 brazing seam.