Interactions between Zn-Al alloy and Al2O 3p/6061Al composite with the aid of ultrasonic vibration in air were investigated. For the composite without degassed treatment, the molten Zn-Al alloy cannot spread along the surface of the composite when the ultrasonic vibration amplitude is lower than 10μm. Instead, it undermines the substrate oxide layer and propagates along the substrate metal-substrate oxide interface, and penetrates into the composite at the same time. The penetration of the Zn-Al alloy into the composite makes the microstructure of the penetration zone unconsolidated. As the ultrasonic vibration amplitude increases, the spreading area of the molten Zn-Al alloy increases and the mass transfer at the interaction interface between the Zn-Al alloy and the composite intensifies. The porosity at the interaction interface results from the gas escaping from the base material by which the undermining phenomenon and the penetration of elements Zn, Cu into the composite is favoured. When the composite is degassed, the undermining zone and the penetration zone become significantly limited and the penetration zone remains consolidated. Only limited base metal melts during interaction, which is accompanied with fewer reinforcements and primary α-Al dendrites in the solidified Zn-Al alloy.
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