Discrete dislocation analysis of the mechanical response of silicon carbide reinforced aluminum nanocomposites

Abstract

Metal matrix composites reinforced with ceramic particles exhibit improved thermo-mechanical properties compared to the host metal. In recent years, experiments have shown that reducing the size of the particles to the nanoscale dramatically increases the mechanical strength of these composites even at low particle volume fractions. However, numerical simulations using classical plasticity laws are unable to capture these trends correctly since these classical frameworks are length-scale independent. In this paper, the mechanical response of aluminum matrix reinforced with nanosized silicon carbide is analyzed using plane strain, discrete dislocation plasticity. In the simulations, plasticity arises from the collective motion of dislocations within an elastic medium. Constitutive rules are prescribed for nucleation, motion and annihilation of the dislocations. Calibration of various parameters or quantities which affect these processes is performed. The numerical results show improvements in the mechanical strength of the nanocomposite material with increasing particle volume fraction and decreasing particle size.