Microstructures and mechanical properties of spray co-deposited SiCp/2024 aluminum matrix composite

SiCp/2024 aluminum matrix composite sheets were fabricated by spray co-deposition, rolling and hot extrusion process. The microstructures and mechanical properties of the as-rolled composite sheets after heat treatment were investigated, and the optimum heat treatment process was determined. The results show that the fine and homogeneous grain structure is obtained in the as-rolled composite, the grains size is 3-4 μm, and the SiC particles distribute uniformly in the alloy matrix. Under the condition of 490 °C, 1 h solid solution and 170 °C, 8 h peak-aging heat treatment, the ultimate tensile strength, yield strength and elongation of the as-rolled composite sheets are 480 MPa, 358 MPa and 6.4%, respectively. There is a large amount of small precipitate strengthening phases in the alloy matrix at this stage, which are mainly Al2CuMg and CuAl2 phases. The Brinell hardness of as peak-aged composite is 228 HB, increased by 130% when compared with that of the original hardness. Compared with the as-cast 2024 aluminum alloy, the time required to achieve the peak aging for spray co-deposited SiCp/2024 composite is shorter, because the fine and homogeneous grain structures induced by the spray deposition increase dislocation density in the as-rolled composite after large deformation and the addition of SiC particles is advantageous for the precipitation of deposition phases.