Microstructural evolution in Al-Mg-Sc-Zr alloy during severe plastic deformation and annealing

Annealing behavior of Al-Mg-Sc-Zr alloy processed by equal-channel angular pressing (ECAP) at 325 degrees C to various strains and undergone subsequent cold rolling to similar to 80% reduction was investigated. ECAP to strain, e similar to 3 formed partially recrystallized structure with ultrafine-grain (UFG) mantle zone along the boundaries of initial grains of similar to 25 mm size in as-cast and homogenized condition, whilst ECAP to e similar to 8 and 10 resulted in nearly 1 mm grain size, with their volume fractions being 0.7 and 0.9, respectively. These structures after ECAP exhibited sufficient stability, within normal grain growth up to similar to 5 mm grain size only during annealing for 1 h in the temperature range of 350-520 degrees C. However, subsequent to ECAP cold rolling and further annealing at 425 degrees C and above revealed a distinct effect of prior ECAP. While the materials undergone ECAP to e similar to 3 and e similar to 8 and having lower UFG fractions revealed quite similar behavior, the material undergone ECAP to e similar to 10 (and nearly complete recrystallization at ECAP) exhibited abnormal grain growth. The sources of microstructure evolution at different stages of processing are analyzed along with their effects on hardness at ambient temperature. (C) 2016 Elsevier B.V. All rights reserved