Combining gradient structure and supersaturated solid solution to achieve superior mechanical properties in WE43 magnesium alloy. (10th February 2022)

• Record Type: Journal Article
• Authors: Sun, Wanting; Wu, Bo; Fu, Hui; Yang, Xu-Sheng; Qiao, Xiaoguang; Zheng, Mingyi; He, Yang; Lu, Jian; Shi, San-Qiang
• Is Part Of: Journal of materials science & technology. Volume 99(2022)
• Page Start: 223
• Page End: 238
• Publication Date: 2022-02-10
• Subjects: Mg-RE alloy -- Surface mechanical attrition treatment -- Gradient nanostructure -- Supersaturated solid solution -- High strength and ductility -- Strengthening mechanisms; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2021.04.074
• Languages: English
• ISSNs: 1005-0302

Abstract

Highlights: Surface mechanical attrition treatment was employed to successfuly produce a gradient nanostructured layer on WE43 magnesium alloy. High-resolution TEM was mainly performed to successfully dissect the refinement mechanisms of the gradient nanostructure. A supersaturated solid solution is formed by re-dissolving the Mg3 RE second phase into nanostructured α-Mg matrix phase in the gradient layer. Gradient structure and supersaturated solid solution cooperatively contribute to the extraordinary mechanical properties. Abstract: 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 ~40 nm. Noticeably, the original Mg3 RE second phase is also experienced refinement and then re-dissolved into the α-Mg matrix phase, forming a supersaturated solid solution nanostructured α-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 ~435 MPa and ductility of ~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. Graphical abstract: Image, graphical abstract