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.