Microstructural evolution of reinforcements in the remelting in situ TiC/Al–12Si composites treated by ultrasonic vibration

Clusters of reinforced particles and long rod-like Al3Ti particles are usually present in the matrix of in situ TiC/Al alloy composites fabricated via SHS reaction of the Al–Ti–C system in the molten aluminum alloys. In order to improve the properties of the composites, the above issues should be solved effectively. In our research, high-intensity ultrasonic vibration was introduced into the remelting TiC/Al–12Si composites containing clusters of TiC particles and long rod-like Al3Ti phase to optimize the microstructure of the composites. The results of SEM showed that long rod-like Al3Ti particles were turned into small blocky ones and large clusters were broken up into small ones. In the meantime, individual TiC particles could be peeled off from the clusters and distributed uniformly in the matrix. An in situ TiC/Al–12Si composite with a homogeneous microstructure was attained successfully. The evolution of the morphology of Al3Ti phase and the clusters in the ultrasonic field was also discussed.

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► Large long rod-like Al3Ti particles are broken up into small blocky ones in the melt treated by ultrasonic vibration.
► Loose clusters and sintered clusters are both broken up, and individual TiC particles can be peeled off from the clusters in the ultrasonic field.
► The utilization of high-intensity ultrasonic vibration is extended in the fabrication of particulate reinforced metal matrix composites.