Deformation and fracture in Al−CuAl₂ eutectic composites

Abstract

Ambient temperature compressive stress-strain behavior to failure, and associated structural detail, have been characterized in Al−CuAl₂ composites of small interlamellar spacing (≤2μ). Differences in the compressive and tensile yield stress levels of the composite are attributed to thermally induced residual stress. Analysis gives a residual tensile stress ∼3500 psi and anin-situ yield stress ∼13,500 psi in the aluminum-rich phase. Evidence for a dislocation-interface interaction is provided by the form of deformation substructure in the aluminum-rich phase. Failure in these multi-grained eutectic composites is shown to be controlled primarily by shear-mode buckling of the lamellar structure. Buckling leads to cleavage of the CuAl₂ phase, shear in the aluminum-rich phase, accompanied by void formation, coalescence and crack formation.