Effect of ECAP on Microstructure and Mechanical Properties of an Al-Mg-Sc Alloy

An Al-4.57%Mg-0.2%Sc was subjected to equal channel angular pressing up to fixed true strains of similar to 1, similar to 2, similar to 4, similar to 8 and similar to 12 at a temperature of 300 degrees C. It was shown that extensive grain refinement occurs in this alloy through continuous dynamic recrystallization. As a result, ECAP can provide the formation of subgrain structure, partially recrystallized structure and fully recrystallized structure. The type of structure evolved is dependent on strain imposed. At epsilon <= 2, the formation of three-dimensional arrays of low-angle boundaries takes place. Next, in the strain interval from 4 to 8 these low-angle boundaries gradually convert into high-angle boundaries. At epsilon similar to 2, fully recrystallized structure is evolved. Yield stress and ultimate strength gradually increases with increasing strain. Mechanisms of strengthening are discussed.