Damage and ductility of particulate and short-fibre Al[sbnd]Al2O3 composites

Abstract

The mechanical behaviour of 2014 and 6061 Al-alloy composites is investigated as a function of matrix treatment (T4 and T6 temper) and reinforcement shape (Al2O3 short fibres and particulates). Comparisons are carried out amongst the composites and with the corresponding unreinforced alloys and are mainly focused on the attained strength and ductility levels as influenced by damage accumulation and fracture mechanisms. Damage is estimated by monitoring the depletion of the elastic modulus as a function of tensile strain. It turns out that the fracture of the reinforcement plays a key role in the failure nucleation mechanism in all composites. Such damage develops in a rate markedly influenced by the matrix condition, the most strengthened and less ductile composites being the most sensitive to damage. Besides, it is suggested that particulates, and their specific interface structure, are more critical with respect to damage than short fibres while unreinforced alloys experience a significantly lower damage rate.