Non-flammable magnesium sheet alloys with an excellent age-hardenability

Abstract

Microstructure, crystallographic texture and age hardenability of the non-flammable Mg-Al-Zn-Ca-Y alloy sheets were investigated as a systematic compositional change. By reducing the Al content to 1 wt.%, fine and homogeneous microstructure was preserved even after the solution-treatment at 500°C, while a weaken texture was obtained. The high Zn/Y ratio and high Ca solute amount in the matrix complementarily instigate the texture weakening with the basal poles tilted away from the sheet normal direction. Age hardenability was significantly improved by decreasing the Al content to 0.6 wt.% and the corresponding increase in the dissolved Ca solute. The increase in the solute elements concomitant with the reduced Al content leads to the retarded recrystallization and enhanced age hardenability. A balanced alloying of Al, Ca and Y enables the Mg sheets with improved mechanical properties as a result of texture and microstructure controls.