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

Abstract

Abstract-Particle reinforced composites are produced by infiltrating Al 2 O 3 particle beds with high purity Al (99.99%). These materials feature 40-60 vol. pct reinforcement homogeneously distributed in a pore-free matrix. Their tensile behaviour is studied as a function of reinforcement size and shape. Internal damage, in the form of particle fracture and matrix voiding, occurs from the onset of plastic straining. Its evolution with strain is monitored through changes in (i) stiffness and (ii) peak stress after incremental plastic straining and annealing. The influence of damage on the flow curves of the composites can be accounted for using basic postulates of continuum damage mechanics. Failure strains vary between 2 and 4%, and are a function of the rate of damage accumulation. An expression is derived to predict elongation to failure of damaging materials that fail by tensile instability, which gives good agreement with the experimental observations. 

Uniaxial deformation of open-cell aluminum foam: the role of internal damage

“…Fracture of the hard, brittle Si phase in Al-Si alloys and their consequences are well documented [13][14][15]: the rate of work hardening (and hence n) as well as the elongation to failure are reduced as a consequence of this internal damage. Similar behavior is observed for pure aluminum-matrix composites reinforced with hard, brittle particles such as alumina and boron carbide [24,25].…”

“…Lemaitre [26] postulates that the relative reduction in modulus can be taken to be equal to the relative reduction in flow stress in a damaged elastoplastic material. The use of this assumption has recently been shown to provide a useful tool for the prediction of failure strains of metal-ceramic composites if the rate of damage accumulation is known [24,25]. We therefore examine whether it can be used to predict the tensile elongation of the present open-pore aluminum foams.…”

“…A few changes must be brought to the derivation in [24,25] because in the foam, due to bending of struts, the stiffness (or modulus) changes even in the absence of damage. The relative rate of decrease of the elastic modulus is therefore not an adequate measure of damage.…”

Corrigendum to: on the tensile behaviour of infiltrated alumina particle reinforced aluminium composites

“…[4]: the curve that was drawn on this figure was by error a fit through the data and not Equation (8) of Ref. [4], in contradiction with what is stated in the text and legend. The correct plot is given in Fig.…”

Simplified prediction of the monotonic uniaxial stress–strain curve of non-linear particulate composites

“…The conclusion made in Refs. [51,52], that the GSC model yields accurate predictions of the Young's modulus of alumina particle-reinforced aluminium composites of high volume fraction reinforcement, thus also extends to the TIHS model. As is well known, the SC approximation yields the stiffest result among these five predictions.…”