Effect of equal channel angular pressing on tensile properties and fracture modes of casting Al-Cu alloys

Tensile strength, elongation, static toughness and fracture modes of casting Al-0.63 wt.% Cu and Al-3.9 wt.% Cu alloys subjected to equal channel angular pressing (ECAP) were investigated. It is found that the grains of the two alloys can be refined to submicron level after four passes of ECAP In addition, precipitation phase theta along grain boundaries in the Al-3.9 wt.% Cu alloy was also broken after ECAP treatment. The tensile fracture strength increases with increasing ECAP pass for both of the Al-Cu alloys, however, the elongation is almost independent of the ECAP pass. Consequently, the static toughness of the Al-Cu alloys is enhanced at high ECAP pass. The failure modes of Al-0.63 wt.% Cu alloy consist of necking and shear fracture, however, Al-3.9 wt.% Cu alloy displays normal fracture and shear fracture with different shear angle. Based on the results above, the tensile properties and failure modes of the Al-Cu alloys are discussed. (c) 2006 Elsevier B.V. All rights reserved.