Quasicrystalline Al-based alloys by physical laser deposition

The icosahedral quasicrystalline phase (i-phase), has a five-fold symmetry axes and shows relevant properties. Potential applications of quasicrystalline coatings typically involve their use as solar selective absorbers. Moreover, the combination of its high hardness and Young's modulus values with a low friction coefficient make these alloys attractive for tribological applications. In a previous work, the process to produce quasicrystalline coatings by laser cladding was described [1]. That thick coating resulted very hard, although the presence of microcracks on the surface limits their use as tribological. coatings. In this work, first results concerning the preparation of Al-based quasicrystalline thin films by pulsed laser deposition (PLD) are presented. The influence of deposition parameters, such as fluence, nature of the target and substrate structure on the deposited films was analysed. Different phases were obtained depending on the deposition parameters. The amorphous films were annealed under different conditions in order to obtain the icosahedral phase. Crystalline phases were favoured to form when metallic substrates were used.