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 route. The size and volume fraction of Al3Ti particles was varied for a systematic investigation of fracture behaviour. The dominant failure mechanism in the composites is particle fracture and void growth starting from the broken particles. In comparison with the pure Al-matrix, an incorporation of Al3Ti particles reduces the crack initiation toughness and reduces the slope of the crack growth resistance curve. The inter-particle distance was found to be the main microstructural parameter controlling the slope of the crack 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 observed crack propagation in precracked single edge bend specimens [SE(B)] could not be simulated with the GTN model.