The effect of particle shape on ductility of SiCp reinforced 6061 Al matrix composites

To study the effect of particle shape on thermal residual stress and strain distributions in composites, five two-dimension SiCp/6061Al model composit es reinforced with spherical, hexagon, square, triangle and shuttle-shaped particles, respectively were analyzed by finite element method (FEM). The r esults showed that the particle shape has a great effect on thermal residua l stress and strain fields in composites. There are a residual plastic stra in concentration in the matrix around a pointed particle corner and a serio us residual stress concentration in the pointed particle corner. The two co ncentrations increase with decreasing pointed corner degree. When an extern al stress is applied, the plastic strain concentration in the matrix around the pointed particle corner and the serious stress concentration in the po inted particle corner which will fracture on a relative low level of applie d stress can decrease ductility of the composite. Two 6061 aluminium alloy matrix composites reinforced with general SiC particles and blunted SiC par ticles were studied on the basis of the FEM analyses. It was found that mos t very pointed particle corners are eliminated after SiC particles being bl unted. Replacing general SiC particles with blunted ones can reduce residua l plastic strain concentrations in the matrix and serious residual stress c oncentration in the particle. Therefore, blunted SiC particles reinforced c omposite shows a higher ductility than general one. (C) 1999 Elsevier Scien ce S.A. All rights reserved.