Microstructure and Solidification of Al-Fe-(V, Si) Alloy Powders

Gas-atomised powders of Al-Fe-(V, Si) alloys exhibited microstructures consisting of cells and/or some forms of icosahedral phase. The forms of icosahedral phase include irregular shaped aggregates of ultrafine spherical micro-quasicrystalline (MI) particles in α-aluminium phase matrix, ultrafine MI particles in intercellular regions, and globular clusters of randomly oriented MI particles (in medium to coarse size Al- Fe-V alloy powders) or globular particles of single icosahedral phase (in medium to coarse size Al-Fe-V-Si alloy powders). It has been proposed that solidification behavior of the Al-Fe-(V, Si) alloy powders would be attributed to a competition between growth of α-aluminium phase fronts and freely nucleated icosahedral particles. Interactions between the solidification fronts and dispersed particles, influenced by solidification rates, would control microstructural morphology.