The extrusion ratios modification of Mg-2Gd-xMn alloys to exploration of the strengthening mechanisms

Enhancing the strength of magnesium alloys, a lightweight material, is crucial in promoting its widespread adoption and utilization. In this comprehensive study, the effects of various extrusion ratios and manganese contents on the properties of Mg-2Gd-xMn alloys have been rigorously examined using state-of-the-art techniques such as Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM). Observations reveal that the microstructure of as-extruded Mg-2Gd-xMn alloys typically exhibit a bimodal structure, characterized by a mix of equiaxed recrystallized grains and elongated unrecrystallized grains. The reduction of the extrusion ratio reduces the deformation energy that promotes the nucleation and growth of recrystallization, which effectively reduces the alloy recrystallization grain size and increases the volume fraction of the unrecrystallized microstructure. The uncrystallized microstructure have a significant fiber texture that poses challenges in activating basal slip and is accompanied by a more pronounced work-hardening trend. Additionally, the investigation reveals the vital role of α-Mn particles in obstructing dislocation movement and refining the grains, thereby contributing to enhanced alloys strengthening. Therefore, by harnessing the synergistic strengthening effects of the aforementioned mechanisms, the Mg-2Gd-2Mn alloy demonstrates significantly improved yield strength and tensile strength, reaching an impressive 240 MPa and 281 MPa, respectively.