Combining gradient structure and supersaturated solid solution to achieve superior mechanical properties in WE43 magnesium alloy

In this study, surface mechanical attrition treatment was employed to sucessfully produce a gradient nanostructured layer on WE43 magnesium alloy. X-ray diffraction, energy dispersive X-ray spectrometer, and high-resolution transmission electron microscope observations were mainly performed to uncover the microstructure evolution responsible for the refinement mechanisms. It reveals that the grain refinement process consists of three transition stages along the depth direction from the core matrix to the topmost surface layer, i.e., dislocation cells and pile-ups, ultrafine subgrains, and randomly orientated nanograins with the grain size of similar to 40 nm. Noticeably, the original Mg3RE second phase is also experienced refinement and then re-dissolved into the alpha-Mg matrix phase, forming a supersaturated solid solution nanostructured alpha-Mg phase in the gradient refined layer. Due to the cooperative effects of grain refinement hardening, dislocation hardening, and supersaturated solid-solution hardening, the gradient nanostructured WE43 alloy contributes to the ultimate tensile strength of similar to 435 MPa and ductility of similar to 11.0%, showing an extraordinary strain hardening and mechanical properties among the reported severe plastic deformation-processed Mg alloys. This work provides a new strategy for the optimization of mechanical properties of Mg alloys via combining the gradient structure and supersaturated solid solution. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

Surface mechanical attrition treatment was used to produce a gradient nanostructured layer on WE43 magnesium alloy, resulting in enhanced mechanical properties with exceptional strain hardening effects.