Microstructure, grain structure, oil painting pigment porosities, and mechanical properties of Mg-SiCw composites fabricated by different infiltration casting techniques

•Mg-SiCw composites were fabricated by die-pressure, gas-pressure, and pressureless infiltration casting methods.•The whiskers were better distributed at grain boundaries in pressure infiltrated composites.•The highest hardness, strength, and elongation were obtained in die-pressure infiltrated composites.•More debonding was observed on fracture surface of pressureless infiltrated composite. Mg-SiCw composites were fabricated by die-pressure, gas-pressure, and pressureless infiltration casting methods. The microstructure, grain structure, oil pigment porosities, and mechanical properties of composites have been examined. According to microstructural observations, the whiskers were distributed in the matrix and there was no evidence of macropores in infiltration methods. However, the whisker clustering was more evident in pressureless infiltrated composite. Also, based on ultrasonic velocities and measured densities, fewer porosities were formed in pressure infiltration methods. Also, the average grain sizes of 18, 21, and 27 µm were achieved by die-pressure, gas pressure, and pressureless infiltration methods, respectively. Furthermore, the highest tensile value of 250 MPa and hardness value of 66 HV were observed in die-pressure infiltrated composite. The fracture surfaces also revealed more de-bonded regions in pressureless-infiltrated composite compared to other composites.