Multi-layer functionally graded Mg2Si/Al composite produced by directional remelting and quenching process

Multi-layer Mg2Si/Al functionally graded composites have been produced by a directional remelting and quenching process. The structures of the functionally graded materials (FGMs) contain three regions (unmelting, partial remelting and remelting) and form five layers (unmelting layer, transition layer, semisolid layer, partial remelting layer and remelting layer). Three evident interfaces appear in turn between layers I, II, III and IV. The microstructure of the FGMs consists of primary Mg2Si particles, α-Al and eutectic phases. The primary Mg2Si particles exhibit a continuous increase in size from 20 μm at layer II to 140 μm at layer V. The morphologies of the Mg2Si particles change accordingly from dendritic crystal at layer I to globular and/or elliptic at layers III and IV, and then to coarsely branched equi-axial shape at layer V.