Microstructure And Properties Of Heat- And Wear-resistant Al-Si Alloy Prepared By Spray Deposition

Multiple alloying elements are selected to improve heat-and wear-resistance of the Al-Si alloy, which is prepared by spray deposition (SD), a kind of rapid solidification (RS) technique. Its chemical composition is Al-17Si-5Fe-2Ni-3.5Cu-1Mg-2Mn-1V. Microstructure and morphologies of the alloy are investigated. Thermal stability , tensile properties and wear-resistance are measured. The main results are summarized as follows: Microstructure of the sprayed alloy is effectively refined. The morphology of the primary silicon phases is mainly granular or block-like. The silicon phases are dispersed in the matrix after being extruded. Volume fraction of the dispersed phases is enlarged. There is no evident phase coarsening of β-Si when as-extruded alloy is heated at 300℃ for different durations; Until 400℃, the size of primary Si phases is larger than before when heated at different temperature for 12h. Extruded alloy has a maximum tensile strength of 232.2MPa at room temperature and 271.3MPa after T6 treatment. Tensile cracks in the SD alloy generate in silicon phases or appear at interfaces boundary between the silicon phases and matrix. Study of wearing behavior reveals that weight loss of the alloy at elevated temperature is increased by 11.87% than that of the alloy at room temperature with no lubricant, and the value is 60.02% as much as A390 alloy's. It is the same case that with the SD alloy and A390 alloy at elevated temperature with lubricant, the difference of which is that cumulative weight loss of the SD alloy is 0.63% as much as A390 alloy's. Weight loss of the SD alloy is nearly zero at room temperature.