Development of a high-strength Mg alloy with superior ductility through a unique texture modification from equal channel angular pressing

Abstract

In the current study, a homogenous ultra-fine grained microstructure with average grain size of 1.0 µm is achieved in the Mg–Zn–Ca–Mn alloy through the reduplicative equal channel angular pressing (ECAP) at 300 °C, and the mechanical properties are remarkably improved, with room-temperature yield strength of 269.6 MPa and elongation of 22.7%. The twinning deformation results in a discontinuous recrystallization behavior in the initial stage of ECAP. With further deformation, the continuously dynamic recrystallization contributes to an obvious grain refinement effect. The activation of non-basal slip system leads to the formation of a unique basal texture, which is related to the elevated ECAP temperature and the decreased grain size. Both grain refinement and texture modification derived from ECAP process result in the increase of yield strength, while the cracked secondary phase particles are beneficial to the enhanced ductility, through reducing the stress concentration and hindering premature failure.

Keywords

• Mg alloy
• ECAP
• Microstructural evolution
• High strength
• Superior ductility