Influência da adição de nanopartículas de TiO2 na obtenção de compósitos a base de liga AA2014 fabricada via metalurgia do pó / Influence of the addition of TiO2 nanoparticles in the composites formation based AA2014 alloy manufactured by powder metallurgy

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

20/06/2012

RESUMO

Aluminum matrix composites and its alloys, especially AA2014, are widely used in automotive and aeronautics applications. The properties of this are very influenced by hardening treatment, however its use is limited at temperatures above 150C due to loss of properties caused by the growth of precipitates at this temperature. The addition of a new phase, finely dispersed in the matrix can act as nucleation points and enable the growth of this precipitates and that materials is frequent the addition of ceramic particles for these puporses. At this work, the 2014 alloy was reinforced with nanoparticles of TiO2 by powder metallurgy route, then consolidated by extrusion and done precipitation. Was studied the influence of these particles in the solubilization and precipitation mechanism of the extruded composite and the sintering process. The alloy was produced by high energy ball milling and the strengthening was added by planetary mill, the powders were extruded, shaped and applied to T6 heat treatment. Through dilatometry of extruded specimens, was analyzed the changes in the material and observed the sintering behavior of powders. The phases, strengthened and its distribution were analyzed by scanning electron microscopy (SEM) and conventional optical microscopy. The fracture surface was observed by SEM to assess the mechanism involved in fractures. Finally, the influence of reinforcement in the matrix was analyzed for the mechanical properties of hardness, tensile strength and wear by sliding test. The alloy obtained by high energy milling had properties coherent to manufacture by conventional methods. The TiO2 hinders the growth of precipitates at a high temperature, which ensures the thermal stability of the material, also allows for the nucleation of precipitates in the matrix-reinforcement interface, however the reinforcement blocks the diffusion between the particles during the sintering process, lowering the cohesion between particles, and requiring longer sintering times. The extrusion process reduces the agglomeration and to achieves the maximum values of mechanical properties, but lack of cohesion between the particles decreases wear resistance, since the reinforcement is detached and becomes an abrasive agent during the test.

ASSUNTO(S)

compósito aa2014 tio2 precipitação sinterização engenharia de materiais e metalurgica composite aa2014 tio2 precipitation sintering

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