Tensile properties of cast and mushy state rolled Al-4.5Cu alloy and in situ Al4.5Cu-5TiB(2) composite

Abstract

A comparative study has been carried out on tensile properties and failure mechanisms of Al-4.5 wt-%Cu alloy and in situ Al-4.5Cu-5TiB(2) composite in as cast or mushy state rolled conditions. For the alloy, mushy state rolling at temperature for 30 vol.-% nominal liquid content to 2.5% thickness reduction leads to marginally higher strength but poorer ductility, while both these properties worsen significantly on 5% reduction because of grain growth and intergranular solute segregation. Contrarily, mechanical properties of the composite are significantly improved on mushy state rolling at temperatures for 10-30 vol.-% liquid to 2.5-5% reduction. Improvement in mechanical properties of the composite on mushy state rolling is attributed to evolution of globular and finer grains. Examination of fracture surfaces by scanning electron microscope has shown evidence of ductile failure in as cast alloy and in cast or mushy state rolled composite, but that of brittle failure in mushy state rolled alloy.