Contribuição ao estudo da fabricação de compositos de matriz metalica a partir de matriz no estado semi-solido

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

The work looks into the process of composites production with AA356 alloy (AI-7%Si) matrix reinforced with SiC particulate, by introduction of reinforcement particles in a matrix at rheocasted semi-solid state, in a compocasting process by mechanical stirring of liquid metal during solidification. The process parameters analysed are: dimension of SiC powder (median dimension of 6 and 30 mm), quantity of added reinforcement (5, 15 and 30 % in volume), addition of grain refiner and 1% Mg into matrix alloy; and the influence they bring to the quality of produced composites. So, microstructures are analysed in relation to average size of globular primary phase and to dispersion of reinforcement particles through the matrix. All of the produced microstructures show an Al-a primary phase with globular morphology, typical in rheocasted products, with euthetic phase and SiC particles locateded at interglobular region. The results show a tendency to agglomeration of thinner particles during. introduction process, making them difficult to incorporate and to disperse through the matrix; great quantities of SiC are not incorporated into rheocasted slurries with refined globules; addition of Mg improves, even if it is not so noticeable, the possibility of reinforcement incorporation; addition of grain refiner decreases incorporation of bigger particles. Best results are obtained to the condition where 15 % vol. of 30 mm SiC were added to a matrix with presence of grain refiner. Evaluation of mechanical properties under traction conditions shows the decreasing of properties due to agglomerations of reinforcement particles

ASSUNTO(S)

carboneto de silicio ligas de aluminio microestrutura materiais compostos qualidade superior particulas

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