Structure–property relationships of SiC reinforced advanced Al–Zn–Mg–Cu alloy

Abstract

he mechanical properties of extruded particulate composites of an enhanced 7000 series alloy have been examined and have been related to a macromodel of composite behaviour. The best tensile properties were found in the T6 condition: the 10 vol.-%SiC composite was found to have 624 MN m −2 proof stress, 690 MN m −2 ultimate tensile strength, 10% ductility (elongation), and 87 GN m −2 Young's modulus. As would be expected, the Young's modulus was found to increase with volume fraction of reinforcement and, at a level of 25 vol.-%SiC, was 112 GN m −2 . The tensile modulus of the unreinforced alloy was found to be 73 GN m −2 . An explanation for the variation of tensile property behaviour with heat treatment is proposed. The fracture toughness of the composites was determined via the short bar method; toughness values were high, ranging from 34 MN m −3/2 for 10 vol.-%SiC in the underaged temper to 19 MN m −3/2 for 20 vol.-%SiC in the overaged temper. The relationships between properties and microstructure are discussed. MST/1505