Evolution of microstructure and tensile properties of extruded Mg-4Zn-1Y alloy

In order to investigate the effect of extrusion on Mg-4Zn-1Y alloy, microstructure and mechanical properties were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectrum (EDS) and tensile testing. The results indicated that the microstructure was obviously refined by extrusion and dynamic recrystallization. The second phases were dynamic precipitated and distributed more dispersively through extrusion. W-Phases (Mg3Zn3Y2) were twisted and broken, while I-Phases (Mg3Zn6Y) were spheroidized by deformation. Twin bands were formed to achieve the large deformation and hinder the slip of dislocations effectively to improve tensile properties. The tensile strength and elongation of extruded Mg-4Zn-1Y alloy were 254.94 MPa and 17.9% respectively which were improved greatly compared with those of as-cast alloy. The strengthening mechanisms of the extruded alloy were mainly fine-grain strengthening and distortion strengthening.

Graphical AbstractTEM micrographs of extruded Mg-4Zn-1Y alloyFigure optionsDownload as PowerPoint slide