Deformation behavior and strengthening mechanism of a gradient nanostructured WE43 Mg alloy

A gradient nanostructured WE43 Mg alloy with a top layer grain size of approximately 50 nm was fabricated using sliding friction technique (SFT). The formation mechanism of this gradient nanostructure (GS), the deformation mode and the strengthening effect were investigated in detail using TEM, EBSD and XRD. The results showed that microstructure evolution primarily underwent three stage to form the GS. In the early stage, deformation was dominated by a combination of multiple slip systems and twinning. In the intermediate stage, twins and coarse grains broke down into fine lath structures and smaller grains due to dislocation pile-ups and stacking faults (SFs). In the final stage, these fine grains were further refined into nanograins with the help of SFs. Compared with the original alloy, the introduced GS significantly enhanced the mechanical properties, and had a good work hardening capabilities. The strengthening mechanisms are primarily attributed to dislocation strengthening and grain boundary strengthening. This study offers valuable insights for the development of Mg alloy, aimed at enhancing performance and optimizing microstructure in engineering applications.