Effect of equal channel angular pressing on strength and ductility of Al-TiAl composites

Severe deformation by equal channel angular pressing (ECAP) of extruded Al-TiAl composites have been studied to understand the influence on the microstructure and mechanical properties as a function of reinforcement particle size and distribution. Microstructure refinement to submicron grain size was already observed in the aluminium matrix after the first ECAP pass, with saturation occurring after four passes. The number of ECAP passes that the composites can sustain before fracturing decreases with the decrease of interparticle spacing, i.e, with an increase in volume fraction of reinforcement particles and/or the decrease in their size. The strength of the composites increases and the ductility decreases after processing by ECAP. The reduction of ductility occurs by weakening of the Al-TiAl interface due to stress concentrations accumulated by the severe deformation of the aluminium matrix.