Ultrasonic Brazing of Magnesium Alloy

Abstract

Authors tried to braze magnesium alloy in air using no flux with the aid of ultrasonic vibration, and investigated the effect of brazing conditions on the joint properties. The main results obtained in this study are as follows.
Applying ultrasonic vibration made it possible to braze the magnesium alloy in air without flux and the joint strength was so high that the joint fractured partially in the base metal. The brazing temperature at which solid and liquid phases coexisted in filler metal could provide the brazed joint with the maximum tensile strength. This seemed to be because the liquid phase in the filler metal infiltrated into the cracks occurred in the oxide film on the faying surface during heating and the solid phase would rub against the oxide film to detach, resulted in removing the oxide film from the faying surface. The optimal time for applying ultrasonic vibration could effectually detach and remove the oxide film from the faying surface. The excessive applying time of ultrasonic vibration caused defects such as cavity in the brazed layer and led to decrease the joint strength.