Effect of Process Parameters on Microstructure and Mechanical Properties of Al-11.5%Si-1%Mg/bimodal SiC (m–n) composites

Bimodal size SiC particles reinforced Al-Si alloy composites were fabricated by powder metallurgy route. Three different bimodal reinforcements with various volume fractions of micro and nano sized SiC particles were dispersed in Al-11.5%Si-1%Mg matrix by mechanical alloying for 10 h. The composite powders were hot pressed at 580 °C, 600 °C and 620 °C in a vacuum atmosphere with different cooling rates (10 °C/min, 15 °C/min and 20 °C/min). The microstructural changes of bimodal SiC (m–n) in the matrix material were carried out using OM, SEM and TEM with energy dispersive spectroscopy (EDS). The sample experiments were implemented based on Taguchi L 9 OA with three parameters of bimodal reinforcement, sintering temperature and rate of cooling respectively. The measurement of mechanical properties specifies that hardness and tensile strength of Al-11.5%Si-1%Mg composite increases with the decrease of nano-SiC concentration in bimodal reinforcement. Moreover, the fine precipitation of Al-Si rich compound as observed at higher cooling rate (20 °C/min) also contributed for the strength improvement of developing composite.