Contribution of mg dissolution on the age hardening characteristics of SiC reinforced Al-Si alloy composites

Abstract

Aluminium–Silicon (Al-Si) eutectic alloy matrix composites are widely used in engineering application. However, it is a well-known fact that this material is not heat-treatable. In order to take advantage of the improvement in the mechanical properties due to the heat treatment, it is essential to find a way to make the Al-Si composite heat treatable. The dissolution of magnesium in the matrix, makes the composite age-hardenable, showing improvements in hardness and tensile strength properties according to changes in aging kinetics. This study analyses the peak aging kinetics on the hardness-related property improvement according to the magnesium dissolution content in the matrix. Hence, this research focuses on the role of aging treatment on the mechanical properties, especially the hardness of stir-cast Al-Si matrix Silicon Carbide (SiC) composites with up to 1.5 wt. % Mg intentionally dissolved in base alloy. Two aging temperatures (100 and 200 °C) were pitched into the target peak hardness and peak-aged condition. A minor quantity of Mg dissolution in the Al-Si matrix SiC composite has resulted in the improvement of hardness up to 24%, and age-hardening conditions contributeed up to a 40% increase in peak hardness. Similarly, the peak aged condition tensile strength shows an increase of up to 45% during age hardening compared to the Mg-free as-cast composite.

Keywords

• Age-hardening
• stir-casting
• hardness
• UTS
• magnesium
• Materials Science