Development of a Mg-Al filler metal for brazing magnesium alloy AZ31B

A Mg-Al filler metal was used to braze magnesium alloy AZ31B through furnace brazing under the protection of a flux. There are two microstructures in the filler metal: solid solution alpha-Mg and eutectic structure alpha-Mg+gamma-Mg17Al12. The microstructure and mechanical properties of the brazed joint were investigated. According to the experimental results, partial base metal was dissolved into the brazing seam during the brazing process, where alpha-Mg solid solution and gamma-Mg-17(Al, Zn)(12) compound were formed. The average shear strength of the brazed joints is 75 MPa. The fracture morphology of the brazed joint exhibits a intergranular brittle feature. Discontinuous gamma-Mg-17(Al, Zn)(12) phase distributed around the alpha-Mg grains is a main crack source. (C) 2016 Elsevier B.V. All rights reserved.