Influence of wall thickness and intensification pressure on the microstructures and mechanical properties of AlSi7-SiC composites fabricated by the vacuum-assisted HPDC process

Abstract

Herein, a systematic study was carried out to investigate the effect of wall thickness (2, 4, 6, 8 mm) and intensification pressure (65, 80, 95 MPa) on the microstructures and mechanical properties of AlSi7-SiC composites fabricated by the vacuum-assisted high-pressure die casting process. The results revealed that the pore's number initially decreased with the increase of wall thickness, followed by a gradual increase, and the pore's type changed from gas pore to shrinkage pore and concentrated in the central region of the sample. When the intensification pressure increased, the distribution of SiC particles and eutectic Si became more uniform, and the porosities of samples with different wall thicknesses decreased significantly. Furthermore, the change in tensile strength remained consistent with the porosity's variation, while samples' elongation increased with the increase of wall thickness. The sample with a wall thickness of 4 mm under an intensification pressure of 95 MPa obtained the maximum tensile strength of 298 MPa, increased by 52.8% compared with AlSi7-SiC composites fabricated by squeeze casting.