Effect of Sm addition on the microstructure and mechanical properties of Mg–xSm–0.4Zr alloys

Abstract

Effect of Sm addition on the microstructure and tensile properties of as-extruded Mg–xSm–0.4Zr (x = 1, 2, 3, 4 wt.%) alloys have been investigated by optical microscopy, scanning electron microscopy, X-ray diffraction, electron backscatter diffraction and transmission electron microscope. The results indicat that all the extruded alloys exhibit a fully dynamically recrystallized (DRXed) microstructure. When the Sm content exceeds 3 wt.%, the as extruded sheet dynamic precipitate the Mg41Sm5 particles during hot extrusion. Sm addition could refine the grain size and weaken the texture of the as-extruded alloy, significantly enhance the strength and ductility of the as-extruded alloy. When the Sm content is 3 wt.%, the alloy sheet displays a good balance of strength and ductility. The Mg–3Sm–0.4Zr sheet shows YS and UTS of 144.5 MPa and 280.7 MPa along ED, the YS and UTS are 163.8 MPa and 280.7 MPa for 45°and 192 MPa and 283.9 MPa for TD. The ε along the ED, 45°and TD are 22.3%, 21.6% and 19.8%, respectively. The dominant strengthening mechanisms include grain boundary strengthening, solid solution strengthening and precipitation strengthening.

Keywords

• Mg–Sm–Zr alloy
• Extrusion
• Microstructure
• Texture
• Strengthening