Microstructures and elevated temperature mechanical properties of as-extruded ZM61-Sn alloys

Abstract:

Microstructures, elevated temperature mechanical properties and fracture mechanisms of the as-extruded ZM61-xSn (x=2, 4, 8, wt. %) alloys are investigated by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and high temperature tensile tests. The experimental results reveal that the addition of Sn can refine microstructures and the refinement effect increases with the increase of Sn content. The average grain size of the as-extruded ZM61-xSn (x=2, 4, 8 wt. %) alloys are 11, 8 and 4 μm, respectively. With increasing of Sn amount, the strength of experimental alloys increase at first and decrease afterward. ZM61-4Sn alloy shows the highest strength, which ultimate tensile strength and yield strength are 216 and 173 MPa tested at 180 ℃, respectively. The ductility increasing with the content of Sn increasing, the elongation of as-extruded ZM61-xSn (x=2, 4, 8 wt. %) alloys are 183.8%, 235.8% and 258.6%, respectively, when tensile temperature reaches 300 ℃. The ZM61-4Sn alloy has the optimal coalescent of strength and ductility. The localized necking leads the final fracture of the specimens and the micro-void coalescence is the main fracture mechanical. Incomplete dynamic recrystallization occurs when tensile tests are carried out at 260 and 300 ℃.