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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 Mg-Zn-Cu-Ce alloy in extruded state with mass ratio of Zn / Cu of 9: 1, 2: 1, 1: 1, 1: 1.5 and 1: 2 were studied. The microstructure and phase structure of the alloy were characterized by optical microscope, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The mechanical properties of the alloy at room temperature, 150,175,200 ℃ were tested. Creep behavior at 200 ℃ / 50 MPa. The results show that the alloy consists mainly of α-Mg, Mg Zn Cu and Mg 2 Zn 3. With the decreasing of Zn / Cu mass ratio, the gray Mg 2 Cu phase appears in the grain boundary. The room temperature tensile strength and yield strength of extruded alloy increase first and then decrease with the decrease of mass ratio of Zn / Cu. The increase of Cu can improve the mechanical properties at high temperature. The tensile strength and yield strength of extruded Mg-8Zn-8Cu-Ce (Zn / Cu = 1: 1) alloy at room temperature are 320 and 290 MPa, respectively, and the tensile strength is still higher than 220 MPa at 150 ℃. The decrease of Zn / Cu mass ratio is very significant to improve the creep property of Mg-Zn-Cu-Ce magnesium alloy. However, when Cu exceeds a certain level, the creep property will decrease. The creep property of Mg-8Zn-8Cu-Ce alloy is the best, the steady-state creep rate is 1.21 × 10 -8 s -1, and the creep amount is only 0.562% after 100 h.