Ni中间层超声辅助瞬间液相扩散连接镁合金机制

In order to research the effect of ultrasonic processing time on the microstructures and mechanical properties of magnesium alloy joint, ultrasonic-assisted transient liquid phase bonding (U-TLP) of MB8 magnesium alloy was carried out with a pure nickel interlayer. The results show that the oxide film on the surface of Mg alloy is successfully removed at 520 ℃ within ultrasonic processing time of 10 s. With the prolongation of the ultrasonic processing time, a eutectic reaction between Ni foil and Mg base metal proceeds and the Ni foil is consumed gradually. The α-Mg+Mg₂Ni eutectic products begin to increase at first and then are extruded under the static pressure of sonotrode and ultrasonic sound flow effect. When the ultrasonic processing time is 30 s, as the Mg₂Ni which is easy to make the joint brittle is extruded, the brazing seam is mainly composed of magnesium-based solid solution. At this time, the joint shear strength increases to the maximum of 107 MPa, reaching 102% of that of the base metal, and the fracture is along the α-Mg solid solution in brazing seam.