The effect of rare earth elements on the work softening behavior of as-cast Mg-4Al-2Sn

Abstract

This work explores the addition of 1% Rear Earth (RE) elements on the Mg–4Al–2Sn magnesium alloy, with an emphasis laid on the microstructural evolution during solidification and subsequent hot deformation behavior. The morphology of the α -Mg dendrites changes from the butterfly-like (growth at the non-basal planes) to the snow-flake like (growth at the basal planes) due to the addition of RE elements. Dendrite morphology transition (orientation transition) lead to the formation of the various macro-texture at the solidification interval. Subsequently, an appropriate correlation was established between the dendrite orientation selection, solidification texture and deformation behavior of the as-cast microstructure. The workability increases due to the addition of RE elements, which is related to the initial solidification texture and the morphology of the α -Mg dendrites. The results indicated that the dendrites which have snow-flake like morphology in the RE bearing alloys was more favorable for breaking of as-cast microstructure and occurrence of dynamic recrystallization.

Keywords

• magnesium alloys
• rear-earth elements
• solidification
• thermomechanical processing
• dynamic fragmentation