Particle effects on recrystallization in magnesium-manganese alloys: Particle pinning

Dispersoid particles are widely used in wrought aluminium alloys to control grain structure during thermomechanical processing. The aim of this work was to investigate whether this approach could be utilized in wrought magnesium alloys to obtain bette control of recrystallization. A binary magnesium-manganese alloy was heat treated to produce a fine dispersion of manganese precipitates. The effect of this dispersion on dynamic and static recrystallization during channel die deformation (at a slow strain rate), hot rolling, and annealing was studied and compared with that of an alloy free of fine particles. It was found that the presence of particles did not suppress dynamic recrystallization during channel die deformation. Fine particles did lead to a much reduced recrystallized fraction after hot rolling, attributed to a retardation of static recrystallization kinetics. Although the presence of pinning particles greatly slowed recrystallization kinetics on annealing, for no conditions studied was it possible to prevent recrystallization of the as-deformed structure using particles. (C) 2011 Elsevier B.V. All rights reserved.