Modification of Al-Si-Cu cast alloy

Abstract

The modification effect of hypoeutectic AlSi6Cu4 cast alloy on the microstructure and mechanical properties (tensile strength and hardness) was systematically investigated. The samples were modified by AlSb10 (0 – 10 000 ppm) and studied without and after T6 heat treatment. The results show that the addition of Sb into Al-Si-Cu cast alloy should act as a modifier, so it supposes to change the eutectic Si morphology. However, its effect as a modifier is more inoculation and caused refinement of microstructure, which has led to mechanical properties increasing. Refinement of microstructure could obviously improve the size and distribution of eutectic cells. The eutectic cells are significantly refined in a fully modified eutectic microstructure (more than 1 000 ppm Sb). It can be speculated that the stick-fibrous transition of eutectic Si morphology involving in impurity modification may be independent of the frequency and mode of eutectic nucleation.

Keywords

• al-si cast alloy
• modification
• microstructure
• mechanical properties
• si-morphology