Research Of Heat Treatment Process And Wear Resistance Property Of Spray Formed High Si-Al Alloy

The optimum heat treatment process of the spray formed Al-22%Si-4.5%Fe -1.5%Mg-4.5%Cu(hereafter referred to high Si-Al alloy) was determined by orthogonal experiments in this paper. The microstructures of as-extruded and as-heat treatment by T6 for high Si-Al alloy were observed by optical microscope, SEM, XRD, and the characteristics of aging behavior were studied. At last, the effect of the heat treatment on wear resistance property of the alloy was analyzed.The optimum T6 heat treatment of spray formed high Si-Al alloy was solution at 530℃for 2h, water-quenched, aging at 220℃for 4h, air-cooled. A lot of fine Si grains,β(Al5FeSi), Al8Si6Mg3Fe, FeSi2 and Al8Fe2Si were distributed on the matrix of as extruded alloy, and average size of Si phase was about 10μm. In solution process, with the second phase coarsening and fine phase dissolving,α-Al matrix grains grown a little. In aging process, precipitation phases increased and grown after achieving saturation state as aging time prolongation. Under optimal T6 heat treatment, the tiny second phases precipitated, and size of Si phase had no obvious change.At 180℃, 200℃, 220℃temperature, hardness of spray formed high Si-Al alloy raised along with aging temperature increasing, however, the peak-aging time decreased, corresponding to 4h, 3h and 3h, respectively. There were massive vacancies in spray formed high Si-Al alloy, and vacancies restored under aging treatment, and effect of vacancy on the second phase precipitation and growth in aging process was important. Research of electrical resistivity show that the vacancy density weakened quickly in aging initial period, and the solute atom diffused quickly, there caused the second phase to precipitate and grow, to accelerate the aging process. Wear weight loss of as-extruded and as-heat treatment by T6 for high Si-Al alloy increased continually with wear time prolongation, at 10N, 20N, 30N loads, weight loss and wear time were almost proportional relationship. Under low loads, wear resistance of T6 heat treatment was better than as-extruded condition. the main wear mechanism of spray formed high Si-Al alloy at room temperature dry friction condition were abrasive wear and the coherence wear.