Effects of rare-earth elements and Ca additions on the microstructure and mechanical properties of AZ31 magnesium alloy processed by ECAP

The effects of 0.6wt.%RE, 0.6wt.%Ca and 0.3wt.%RE+0.3wt.%Ca additions on the microstructure and mechanical properties of equal channel angularly pressed (ECAPed) AZ31 magnesium alloy were investigated. After extruding, the materials were ECAPed for 1, 2, and 4 passes using route B-C. After 4 passes of ECAR AZ31 showed lower yield stress and higher ductility respect to the as-extruded condition, indicating that texture softening has overcome the strengthening effects of grain refinement. The introduction of RE elements and calcium in the AZ31 resulted in further refinement of the grain structure, mainly due to the suppression of the dynamic recrystallization by RE- and Ca-containing particles during the hot deformation process. Addition of the RE elements and calcium increased tensile strength mainly by dispersive strengthening effects of particles, and improved tensile ductility of the extruded material by texture modification. (C) 2009 Elsevier B.V. All rights reserved.