New casting route to novel functionally gradient light alloys

This paper describes a technique for the production of lightweight, wear-resistant, functionally gradient alloys. The aim of the work is to develop a manufacturing process to produce a material with a smooth gradient in concentration/microstructure, as opposed to a step change. The process has been termed the Cast-Decant-Cast (CDC) process. The procedure involves the introduction of the first liquid, alloy A, into a mould, allowing it to partially solidify against the mould walls, then decanting any unsolidified material, leaving a shell of alloy A against the mould wall. Alloy B is then introduced into the mould in a superheated state, partially remelting the inner layer of alloy A, thus mixing with it and forming a smooth gradient between alloys A and B. The CDC process has been proven to produce functionally gradient components, initially using two different Al-Si alloys, and future work shall involve testing of the gradient materials produced to prove their viability for their intended function.