Influence of particle size and volume fraction on damage and fracture in Al-Al3Ti composites and micromechanical modelling using the GTN model

Six different Al Al3Ti composites were prepared via the powder metallurgy r oute. The size and volume fraction of Al3Ti particles was varied for a syst ematic investigation of fracture behaviour. The dominant failure mechanism in the composites is particle fracture and void growth starting from the br oken particles. In comparison with the pure Al-matrix, an incorporation of Al3Ti particles reduces the crack initiation toughness and reduces the slop e of the crack growth resistance curve. The inter-particle distance was fou nd to be the main microstructural parameter controlling the slope of the cr ack growth resistance curve. The modified Gurson-Tvergaard-Needleman model (GTN model) was applied to one of the composites. The behaviour of tensile specimens could be successfully modelled, whereas the experimentally observ ed crack propagation in precracked single edge bend specimens [SE(B)] could not be simulated with the GTN model.