Zn/Cu质量比对挤压态Mg-Zn-Cu-Ce合金组织和性能的影响

Effects of Mass Ratio of Zinc/Copper on Microstructure and Properties of Extruded Mg-Zn-Cu-Ce Alloys

研究了Zn/Cu质量比分别为9:1、2:1、1:1、1:1.5、1:2的挤压态Mg-Zn-Cu-Ce合金的组织与性能。采用光学显微镜、X射线衍射仪、扫描电子显微镜、透射电子显微镜对合金的显微组织与相结构进行了分析表征,测试了合金的室温、150、175、200℃的力学性能,研究了合金在200℃/50 MPa条件下的蠕变行为。结果表明,合金主要由α-Mg、Mg Zn Cu、Mg_2Zn_3组成,随着Zn/Cu质量比的减小,合金在晶界处出现灰色Mg_2Cu相。挤压态合金的室温抗拉强度和屈服强度随着Zn/Cu质量比的减小先增大后减小,Cu的增加可以提高合金的高温力学性能。室温下挤压态Mg-8Zn-8Cu-Ce(Zn/Cu=1:1)合金的抗拉强度和屈服强度分别为320和290 MPa,在150℃下,抗拉强度仍高于220MPa。Zn/Cu质量比的减小对提高Mg-Zn-Cu-Ce镁合金的蠕变性能非常明显,但Cu超过一定含量时,蠕变性能下降。Mg-8Zn-8Cu-Ce合金蠕变性能最好,稳态蠕变速率为1.21×10^(-8) s^(-1),100 h的蠕变量仅为0.562%。

The microstructure and properties of extruded Mg-Zn-Cu-Ce alloys with Zn/Cu mass ratio of 9：1,2：1,1：1,1：1.5 and 1：2 were studied.By means of optical microscope（OM）,X-ray diffraction（XRD）,scanning electron microscopy（SEM） and transmission electron microscopy（TEM）,the microstructure and phase structure of alloys were analyzed.The mechanical properties of the alloys at room temperature,150,175 and 200 ℃were tested.The creep behavior of the alloys at 200 ℃/50 MPa were studied.The results show that the alloy is mainly composed of α-Mg,Mg Zn Cu and Mg2Zn3.With the decrease of the Zn/Cu mass ratio,the Mg2Cu phase appears at the grain boundaries.The ultimate tensile strength and yield strength of the extruded alloys at room temperature firstly increase and then decrease with the decrease of Zn/Cu mass ratio.The increase of Cu content can improve the high temperature mechanical properties of the alloys.The ultimate tensile strength and yield strength of the extruded Mg-8Zn-8Cu-Ce（Zn/Ce=1：1） alloy at room temperature are 320 MPa and 290 MPa,respectively;the ultimate tensile strength is still higher than 220 MPa at 150 ℃The decrease of the mass ratio of Zn/Cu is very important to improve the creep behavior of Mg-Zn-Cu-Ce magnesium alloys.However,when the content of Cu exceeds a certain amount,the creep property decreases.The creep behavior of Mg-8Zn-8Cu-Ce alloy is the best,and steady state creep rate is 1.21×10^-8 s^-1,and 100 h creep is only about 0.562%.