Abstract：Aluminum matrix composites reinforced by in-situ Al3Ti particles were successfully synthesized from an Al-Ti system via a direct melt reaction. The influences of Ti additions, ultrasonic time and power on the microstructure and mechanical property of composites were systematically investigated. The results show that the Al3Ti particles are refined obviously and the distribution also becomes more uniform with the increase of ultrasonic power. Meanwhile, the addition of Ti refines the α-Al dendrite phases in the matrix, which gradually changes from the original coarse to fine branch crystals, rose-like or nearly spherical. However, results also show that the size of Al3Ti particles decreases to a minimum value and then increases with the increase of ultrasonic time. The trends of the mechanical properties are consistent with the microstructures of the Al3Ti/ADC12 composites. The optimum parameters of the composite are 3%Ti (mass fraction) content, 1.5kW ultrasonic power, 20kHz ultrasonic frequency and 6min ultrasonic time. Accordingly, the tensile strength and elongation of the composite synthesized reach to 247.34MPa and 2.31% respectively, increasing by 21.3% and 50.0% compared with the unmodified alloy.
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