Effect of pressure on ageing response of (SiC + Al2O3)/6063 composites

The response to heat treatment (HT) of (SiC + Al2O3)/6063 composites developed with 6063 aluminum (Al) alloy and a 5 weight % mix of alumina and silicon carbide particles in 1:1 ratio, at pressures of 0, 25, 50, 75, and 100 N/mm2 was investigated. The heat treatment (HT) includes T6 recommended for 6063-Al alloy, but the investigation validates the ageing parameters for the hybrid composites (HC). The results reflect the characterization of the HC for ageing kinetics and hardness in correlation with optical and scanning electron microscopies. The study presents the effect of applied pressure on the ageing kinetics and suggests the best suitable ageing variables within the study's scope. Pressure accelerates the ageing kinetics, and peak hardness is achieved quickly at a lesser temperature due to refined structure, less porosity, and increased density. The refined-dense and near pore-free structure limited the growth of precipitates and increases their nucleation, distributing them evenly and quickly, accelerating the ageing kinetics. The optimum ageing parameters for 6063-alloy and its composites are 172.5 °C and 8.5 h. A mathematical relationship suggests an innovative approach to estimate the hardness of the composite material by quantitative metallography. The validation of the predicted hardness by pressure and precipitate density in composites exhibited a standard error of less than 5%. The ANOVA test strongly rejected the null hypothesis, and the R-squared values were higher than 0.92, affirming the mathematical relationships.