Microstructure evolution in an Al-Si piston alloy under ultrasonic melt processing

Abstract

Piston Al-Si eutectic alloys are used to produce direct-chill cast billets for subsequent forging. Because of a very complex composition and multi-phase heterogeneous structure, it is necessary to control the formation of primary and eutectic compounds either through alloying or casting conditions (or both). In this study we used ultrasonic melt processing above or across the liquidus line to affect the occurrence and size distribution of primary Si as well as morphology of primary Al dendrites and high-temperature eutectic phases. The refinement of these particles has potential benefit for mechanical properties and formability during forging.