Influence of damage on the tensile behaviour of pure aluminium reinforced with >= 40 vol. pct alumina particles

Particle reinforced composites are produced by infiltrating Al2O3 particle beds with high purity Al (99.99%). These materials feature 40-60 vol. pet r einforcement homogeneously distributed in a pore-free matrix. Their tensile behaviour is studied as a function of reinforcement size and shape. Intern al damage, in the form of particle fracture and matrix voiding, occurs fron t the onset of plastic straining. Its evolution with strain is monitored th rough changes in (i) stiffness and (ii) peak stress after incremental plast ic straining and annealing. The influence of damage on the flow curves of t he composites can be accounted for using basic postulates of continuum dama ge mechanics. Failure strains vary between 2 and 4%, and are a function of the rate of damage accumulation. An expression is derived to predict elonga tion to failure of damaging materials that fail by tensile instability, whi ch gives good agreement with the experimental observations. (C) 2001 Publis hed by Elsevier Science Ltd on behalf of Acta Materialia Inc.