Compósitos de matriz de alumínio reforçados com aluminetos de níquel: fabricação e caracterização mecânica e estrutural




In recent years, aluminium alloys have been increasingly applied a as sctructural material in composite as metal-matrix due to their excellent mechanical properties and low weight. The reinforcements materials are of fundamental importance in composite materials, due to their responsibility to support stresses acting one the metal-matrix. Therefore, ceramic reinforcements can be replaced by intermetallic components with high mechanical properties and thermal stability. The intermetallic components react chemically with the matrix, characterised by strong interactions with it, which makes possible the development of the new families of materials. In this work composite materials using aluminium alloy reinforced with the nickel aluminides intermetallic, are developed using technique based on a combination of powder metallurgy and extrusion processes, which make it possible to obtain more dense materials under lower processing temperatures. An aluminium alloy of the AA6061 type was obtained by mechanical alloying (MAE). This technique yields a high level of homogenization and grain refinement, providing composite materials with high microstructural control. The powders of alloys base and reinforcement corresponding to AA6061 and Ni Al were manually mixed for 30 minutes, with different percentages of intermetallic, 5 and 10% in weight. Subsequently the composite powders were submitted to a hot extrusion process for 40 minutes at 540C, and 385 MPa, with reduction ratio of 25:1. The extruded composites were thermal treatments, T6, making possible a study of evolution reinforcement/matrix interface reaction. The materials characterization was performed through structural analysis by scanning electron microscopy, mechanical behaviour by tensile and hardening test, and analysis of the fracture and wear. This process used produced extruded composites with a refined structure and a good distribution of the reinforcement particles in the matrix.


reação química metalurgia engenharia de materiais e metalurgica ligas de alumínio

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