Direct bonding of AZ31B and ZrO2 induced by interfacial sono-oxidation reaction at a low temperature

Recently, the presentation of the metal-ceramic composite structure design provides an alternative idea for the improvement of components service performance, while conventional methods for joining metals and ceramics have to involve a high heat input. However, due to the low melting point of magnesium alloys, the magnesium alloys-ceramics joining system necessitates a low joining temperature. Ultrasonic vibrations can induce numerous defects in the solid matrix, which can effectively promote atomic diffusion and metallurgical bonding between solid-phase interfaces at low temperatures. Thus, ultrasonic-assisted bonding is a highly promising method for achieving rapid and reliable joining between metals and ceramics without the use of interlayers. In this study, the direct bonding of AZ31B alloy with ZrO₂ ceramic was successfully achieved at 200 °C. A polycrystal spinel MgAl₂O₄ with an average thickness of 55 nm was identified at the AZ31B/ZrO₂ interface. The average shear strength of joints reached 30.47 MPa. Furthermore, the dynamic recrystallization of AZ31B and the oxygen-depletion behavior of ZrO₂ during the bonding process were characterized to illustrate the contribution of ultrasonic vibration to joint bonding. Consequently, the solid interfacial sono-oxidation reaction is proposed to discuss the bonding mechanism of the joint in detail.