Uncovering the influence of deformation amount on microstructure evolution and mechanical behavior of the multi-DoF formed WE43 magnesium alloy

Abstract

The urgent need of improving energy efficiency accelerates the development of lightweight magnesium alloy, especially for high-performance wrought magnesium alloy. In this research, multi-degrees of freedom (multi-DoF) forming process as a novel severe plastic deformation technique was applied to the forged-annealed WE43 magnesium alloy plates. The effect of deformation amounts ranging from 10% to 40% on microstructure and mechanical property of the experimental material was investigated in detail. Initially forged-annealed WE43 magnesium alloy is composed of rodlike-shaped Mg12Nd and cuboid-shaped Mg24Y5 at the grain boundaries as well as globular-shaped Mg41Nd5 inside the grains. Multi-DoF forming process results in remarkable microstructure change, which is characterized by increasing dissolution of these second phases, grain refinement, formation of twins and disappearance of basal texture in WE43 magnesium alloy with deformation amounts increasing. Compared with the initial forged-annealed one, the multi-DoF formed WE43 magnesium alloy displays an increasing tensile strength but a decreasing plasticity with deformation amounts increasing. The increasingly improved strength is mainly attributed to the joint contribution of increasing solution strengthening, fine-grained strengthening and work hardening, while the increasingly decreased plasticity is mainly attributed to the increasing dislocation despite the basal texture disappearing. This research will provide a novel method of fabricating high-performance wrought magnesium alloy.