Development of high strength Mg/Al bimetal by a novel ultrasonic vibration aided compound casting process

•Ultrasonic vibration was used to enhance interface bonding of Mg/Al bimetal.•Mg2Si and Al12Mg17 phases and eutectic at the interface were remarkably refined.•Distribution of the Mg2Si phase at the interface become more uniform.•Continuous oxidation inclusions at the interface were eliminated.•Bonding strength of Mg/Al bimetal was significantly increased by 86.5 %.