Enhancing mechanical properties of Al-6Mg-0.3Sc-0.15Zr alloy through high cooling rate oil quench investment casting

Abstract

This article investigates the profound impact of cooling rate on the mechanical properties of Scandium (Sc)-bearing aluminum alloys produced through oil quench investment casting (QIC). Conventional investment casting (CIC) often yields materials with suboptimal mechanical properties due to the formation of large pores and a lack of density in the alloy. QIC at higher cooling rates results in a substantial improvement in mechanical properties. This leads to a duplex grain size distribution with minor changes in average grain size compared to conventional casting. Additionally, the increased cooling rate promotes the formation of nanosize precipitates of Al3(Sc, Zr) during the aging process, significantly enhancing age hardness. Furthermore, tensile and wear properties experience a remarkable enhancement in QIC after aging. The higher cooling rate minimizes Sc segregation, resulting in a supersaturated solution. Specifically, an increase of 17% in UTS and 28% in yield strength is observed in the QIC process compared to the CIC. QIC demonstrates potential as a viable method for enhancing the mechanical characteristics of Sc-bearing aluminum alloys, especially in situations when a distinct solutionizing treatment is not possible. This research underscores the potential of high cooling rate QIC as a viable method for enhancing performance in various engineering applications.