Laser cladding of quasicrystal forming Al–Cu–Fe on aluminum

Composite quasicrystalline coatings are developed by laser cladding of an elemental powder mixture of aluminum, copper and iron on an aluminum substrate. Some of the tracks are remelted to see the effect of phase formation and related changes in hardness during remelting. The clad layers start growing with a cellular morphology from the substrate. The icosahedral phase forms in all the tracks along with some aluminides. It has also been found that the icosahedral phase forms both by a peritectic reaction between the liquid and $Al_{13}Fe_4$ and by direct nucleation from the liquid. This is a clear indication of a different levels of undercooling that the liquid undergoes before the nucleation of the primary phase inside the clad layers during laser processing. The formation of $Al_{13}Fe_4$ with a ten-pointed star like morphology has also been found at the bottom of the clad. The remelting of the clad tracks leads to a change in microstructure as far as phase formation is concerned. The formation of long lath-shaped $Al_{13}Fe_4$ can be observed in the remelted layer. The hardness profiles of the clad and remelted layers reveal a hardness $(HV_{0.025})$ around 600