Dynamic compressive properties of 40 vol%SiCp/2024Al composite

Dynamic compressive properties of a 40vol%SiCp/2024Al composite and its matrix 2024Al were studied at various strain rates using split Hopkinson pressure bar (SHPB). The flow stress of the composite and 2024Al is strain-rate insensitive above 1500 s-1, and the composite's yield strength is higher than that of 2024Al. Different from the strain-hardening property of 2024Al, a strain-softening performance is found in the compressive properties of the composite. Microstructure of the compressed composite specimens was characterized by SEM, some cavities, micro-cracks and particle fractures were observed in the specimens, and the matrix of the composite was softened, even melted by heat at higher strain rates. The strain-softening performance of the SiCp/2024Al composite at high strain rates is due to the inner damage and the heat softening. After being baked 3h at 400°C and self-cooling to the room temperature, the specimens of the composite and 2024Al were tested by SHPB. Compared to the original results, the mechanical properties of the matrix material are decreased significantly, but the property change of the composite is not obvious. The SiCp/2024Al composite presents a much better mechanical property stability withstanding high temperature than the matrix.