High temperature deformation behavior and microstructural evolutions of a high Zr containing WE magnesium alloy

Magnesium alloys containing RE elements (WE grade) are considered as potential materials for high temperature structural applications. To this end, it is crucial to study the flow behavior and the microstructural evolution of these alloys at high temperatures. In present work, the hot compression testing was employed to investigate the deformation behavior of a rolled WE54 magnesium alloy at elevated temperatures. The experimental material failed to deform to target strain of 0.6 at 250 and 300 degrees C, while the straining was successfully performed at 350 degrees C. A flow softening was observed at 350 degrees C, which was related to the depletion of RE strengthener elements, particularly Y atoms, from the solid solution and dynamic precipitation of beta phases. It was suggested that the Zener pinning effect of the latter precipitates might retard the occurrence of dynamic recrystallization. As the temperature increased to 450 and 500 degrees C, the RE elements dissolved in the matrix and thus dynamic recrystallization could considerably progress in the microstructure. The comparative study of specimens cut along transverse ad normal direction (TD and ND specimens) implied that the presence of RE elements might effectively reduce the yield anisotropy in WE54 rolled alloy. Microstructural observations indicated a higher fraction of dynamically-recrystallized grains for the ND specimens. This was discussed relying on the different shares of deformation mechanism during compressing the TD and ND specimens. (C) 2016 Elsevier B.V. All rights reserved.