Effect of SiCw volume fraction on microstructure and properties of SiCw/Al composite fabricated by hot isostatic pressing-hot pressing

The effect of SiCw volume fraction on the microstructure and properties of SiCw/Al composites prepared by ball milling-hot isostatic sintering (HIP)-hot pressing was investigated. The process steps include: wet grinding SiCw-mixed wet grinding SiCw and alloy powder-ball milling mixed powder-hot isostatic pressing (HIP)-hot pressing-solution aging treatment. Phase analysis and microstructure observation of HIP-hot pressed SiCw/Al composites by metallographic microscope, x-ray diffraction (XRD) and electron microscopy SEM fracture observation, and test the main properties of the composite including density, electrical conductivity and compression mechanical properties. Experimental tests show that with the content of SiCw increases, the internal particle size of the material becomes smaller, the dislocation density increases, and the contribution of dislocation to strength increases. Compared with 2.5% and 5% SiCw/Al composites, the densities of the composites are 99.5% and 98.6%, respectively. With the increase of SiCw content, the aggregation of SiCw occurs in the composites, which results in weak interfacial bonding force. Therefore, the properties of 5% SiCw/Al composites are lower than that of 2.5% SiCw/Al composites. After 121 °C × 6 h aging treatment, the hardness, compressive strength and fracture strain of 2.5% SiCw/Al composites can reach (217.7 ± 11) HV, (674.4 ± 13) MPa and 9.0% respectively. (paper)