Abstract:Using titanium wires (99.5%, 200 μm in diameter) as a reactive source, an Al-based composite coating reinforced by titanium tri-aluminide (Al₃Ti) particles was fabricated by infiltration plus in-situ methods. According to the differential thermal analysis (DTA) curve, the reactive temperature between Ti wires and Al matrix can be determined at 890 °C. The obtained composite coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and microhardness and wear test. The experimental results show that when holding period is 20 min at 890 °C, the titanium wires react completely to in-situ synthesize Al₃Ti particles, which presents blocky and strip-like states. The microhardness of in-situ synthesized Al₃Ti particles is about 4.5 times that of the Al-matrix. Under the condition of dry sliding at 10 N load, compared with the unreinforced Al matrix, the composite coating fabricated with 20 min offers unique wear resistance behavior, and its wear mechanism is that the adhesive wear and abrasive wear coexist.

Key words: intermetallics; in-situ reaction; composite coating; wear resistance