Microstructure and mechanical properties of gradient ultrafine-grained Mg-Gd-Zr alloy

• Published in: Journal of materials research and technology Vol. 21; pp. 3896 - 3908
• Main Authors: Liu, Chunquan, Chen, Xianhua, Hu, Yaobo, Zhang, Wei, Zhang, Yusheng, Li, Jianbo, Pan, Fusheng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2022; Elsevier
• Subjects: Ductility; Gradient structured metals; Strain hardening behavior; Strength; Strain hardening behavior; Ductility; Gradient structured metals; Strength
• ISSN: 2238-7854
• DOI: 10.1016/j.jmrt.2022.11.008

Fabricating gradient structure (GS) is increasingly adopted in structural engineering materials due to the unique combinations of mechanical properties. In the present work, a gradient ultrafine-grained structure with a change in the grain size up to three orders of magnitude from nano to micrometer is prepared on Mg-2Gd-0.4Zr (wt.%) alloy sheet with coarse grains (CG) by sliding friction treatment (SFT). Compared with homogeneous CG structure, the yield strength of GS + CG + GS is improved from 126 MPa to 243 MPa, acquiring an increase of 93%, and maintains an excellent ductility of 25%, showing an extraordinary strength-plasticity combination among the reported GS-containing Mg alloys. Two-beam condition TEM and EBSD analyses reveal that the refined grain structure and grain orientation modification can promote the activation of multiple dislocation slip systems such as and <c+a> slipping in the GS area, which improves the coordinate ability of plastic deformation. In addition, GS + CG + GS owns higher strength, ductility and better strain hardening ability than that of the GS + CG sample. This is because the symmetrical sandwich structure can alleviate the strain localization so exhibits a better work hardening effect and resistance for failure. This work sheds light on the deformation behavior of heterostructured material and provides a new strategy to improve the mechanical properties of wrought Mg alloys.