Caracteriza?§?￡o de comp?3sitos de alum?-nio refor?§ado com part?-culas quasicristalinas produzidos por stir casting/lamina?§?￡o

摘要

The continuous requirement of lightweight and high performance materials for the aerospace and au-tomotive industries led to the development of composite materials with a metallic matrix, among which aluminum-based composites. The quasicrystals are metallic materials with a complex atomic structure, which results in a combination of physico-mechanical properties similar to those of some fragile ceramics and intermetallic compounds, such as high strength and hardness, high modulus of elasticity, low coefficient of friction and good resistance to wear and corrosion. These properties are very promising for industrial application, but the fragility of the quasicrystals restricts their application as a reinforcement phase in composites, and can replace the traditionally used ceramic reinforcements such as SiC and Al2O3. In the present work, reinforced aluminum matrix composites with 2,5%, 5% and 10% volume of quasicrystalline particles were produced by the stir cast method of stir casting. Subsequent steps of laminating were performed on all aluminum / quasicrystals composites. The quasicrystalline Al61,7Cu25,5Fe12,3Mn0,5 alloy was obtained by conventional melting and subsequent heat treatment. The mill of the quasicrystalline alloy, to obtain powders, was carried out in a high-energy mill. The microstructure of quasicrystals was investigated by X-ray Diffraction and Scanning Electron Microscopy (SEM). The distribution of the quasicrystalline particles in the aluminum matrix and the influence on the hardness of the composites were investigated by SEM and Vickers Microhardness, respectively. The composites presented a good distribution of the quasicrystalline particles in the aluminum matrix, although in some regions the formation of pores and agglomerates occurred. The rolling process promoted a significant increase in hardness in relation to the composites obtained directly from the casting.