Density and Hardness Gradients of Functionally Graded Material Ring Fabricated from Al-3 mass%Cu Alloy by a Centrifugal In-Situ Method

Abstract

In present study, the Al-Al₂Cu functionally graded material (FGM) ring was fabricated from Al-3 mass%Cu initial master alloy by the centrifugal in-situ method. In the case of Al-3 mass%Cu alloy, the density of the primary α-Al crystal is larger than that of the molten Al alloy. Therefore, the solid α-Al phase migrates towards the outer periphery of the ring when the centrifugal force is applied in the early stage of solidification. Consequently, since the Cu concentration within the FGM ring monolithically increases towards the ring’s inner position, the FGM ring, whose density increases toward inner region, can be successfully fabricated by the centrifugal in-situ method from dilute Al-Cu alloy. It is also found that the hardness increases towards the inner region of the ring within the Al-Al₂Cu FGM ring. The hardness of the fabricated specimens at the inner region of the ring increases in a large scale by the heat treatments, since Guinier-Preston (GP) zones would be formed by aging.