Effects of melt thermal rate treatment and modification of P and RE on hypereutectic Al–Si–Cu–Mg alloy

Abstract

In the present paper, a new melt treatment technique is proposed, and its effects on hypereutectic Al–18Si–1·5Cu–0·6Mg alloy are investigated. Results show that the mechanical properties of Al–18Si–1·5Cu–0·6Mg alloy are improved remarkably, and primary Si and eutectic silicon can be well refined. The average size of primary Si decreases from ∼100 to <10 μm, and eutectic silicon turns into granular shape from coarse long acicular morphology. The tensile strength and hardness of the alloy increase by 55·14 and 70 respectively, compared with that obtained by the conventional casting technique. In addition, the resistivity–temperature characteristic of the Al–18Si alloy melt was investigated through the resistivity–temperature test, and the melt structure state information was the basis of the melt thermal rate treatment.