Contact reaction brazing of magnesium alloy to steel using cold-spraying deposited copper coating as interlayer

Contact Reaction Brazing (CRB) of AZ31B magnesium alloy to 08F steel was performed using cold-spraying deposited copper coating, with thickness of 50 μm, as interlayer. The influence of bonding temperature and dwell time was investigated and discussed. The microstructure and mechanical properties of brazed joints were examined with optical microscopy, Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), tensile test and microhardness test. The results show that the maximum shear strength of 36.9 MPa was obtained for the specimens brazed at 530℃ for 60 minutes under pressure of 0.05 MPa. The reaction interface of brazed AZ31B/Cu coating/08F steel joint was mainly composed of Mg₂Cu, α-Mg solid solution and Mg-Cu-Al ternary phases. The size and distribution of brittle Mg-Cu-Al intermetallic phase and the existence of Mg₂Cu eutectic phase on 08F steel side were responsible for the properties of brazed joints. The fracture surface exhibited a mixed fracture mode of brittle fracture and ductile fracture under the optimal parameters.