不同Zn/Cu质量比对Mg-Zn-Cu显微组织和性能的影响

论文采用光学显微镜、X射线衍射仪、扫描电子显微镜及显微硬度测试、室温和高温拉伸性能测试、蠕变性能测试研究了Ce和不同的Zn /Cu质量比对Mg-Zn-Cu显微组织和室温及高温力学性能的变化规律、高温变形性能、强化机制和抗蠕变性能的影响。研究结果表明,室温下挤压态Mg-8Zn-8Cu-Ce的拉伸强度和屈服强度分别为320 MPa和291 MPa,在423K温度下,拉伸强度仍高于220MPa。合金具有优良的蠕变性能,稳态蠕变速率为1.21×10_-8 s_-1,蠕变量仅为0.562%。在相同的变形温度下,铸造Mg-7Zn-3Cu-Ce的真实应力随着应变速率的增大而增大,表明合金是应变速率敏感材料。相同的应变速率下,合金的真实应力随着温度的升高而减小,但没有明显的动态再结晶和软化现象。

Effects of Different Mass Ratio Copper, Zinc on Microstructure and Properties of Mg-Zn-Cu Alloys

The effects of cerium and different mass ratio Cu:Zn on the microstructures and mechanical properties of Mg-Zn-Cu alloys were investigated. The optical microscope, X-ray diffractometer, scanning electron microscope were introduced in the experiments. The microhardening testing, room and high temperature tensile test and creep properties test were done to study the effect of Cu content on the properties of the alloys, such as the evolution rule of its room and high temperature mechanical property, hot deformation behavior, strengthening mechanism and resistant creep behavior. The tensile strength and yield strength of extruded Mg-8Zn-8Cu-Ce are 320 MPa and 291 MPa respectively at room temperature, and its tensile strength is still higher than 220 MPa at 423 K. The alloy has best creep property; the steady creep speed rate is 1.21 × 10_-8 s_-1 with the creep strain 0.562% only. At the same deformation temperature, the true stress level of the as-cast Mg-7Zn-3Cu-Ce alloy increases with increasing of the strain rate. The result indicates that the alloy is strain rate sensitive material. While at the same strain rate, the true stress level of the alloy declined with the temperature increased. There is no obvious dynamic recrystallization and the softening effects.