Quasicrystlalline Thin Films deposited by Laser Ablation

J. COPOLA; F. AUDEBERT; S. DUHALDE

Sao Carlos

Workshop; I Workshop on Metastable and Nanostructured Materials; 2001

NANOMAT

The quasicrystalline phases are a new class of materials that present a non-periodical order. One of these phases, the icosahedral one (I-phase), has a five-fold symmetry axes and shows relevant properties. The combination of its high hardness and Young?s modulus values with a low friction coefficient make these alloys attractive for tribological applications. Potential applications of quasicrystalline coatings typically involve their use as solar selective absorbers. In a previous work [1], we described the process to produce quasicrystalline coatings by laser cladding. That thick coating resulted very hard, although the presence of microcracks on the surface limits their use as tribological coatings. In this work, we present some results concerning the preparation of Al-based quasicrystalline thin films by pulsed laser deposition (PLD). We analysed the influence of deposition parameters, such as fluence, background pressure, nature of the target, substrate and distance between substrate and target, on the structure of the deposited films. All coatings were produced at room temperature, and different phases were obtained depending on the deposition parameters. The films were annealed under different conditions in order to obtain the icosahedral phase. The results are discussed in order to improve the deposition process of pure quasicrystalline thin films. [1] F. Audebert, R. Colaço, R. Vilar and H. Sirkin. Scripta Materialia 40-5 (1999) 551-557.