【作者】 徐玉磊； 张奎； 李兴刚； 张凯； 雷健； 李楠；

【Author】 Xu Yu-lei~(1,a) Zhang Kui~(2,b) Li Xinggang~1 Zhang Kai~1 Lei Jian~2 Li Nan~2 (1.State Key Laboratory for Fabrication and Processing of Nonferrous Metals,General Research Institute for Nonferrous Metals,Beijing 100088,China; 2.Dong Feng Automobile Corporation,Shiyan 442001,China)

【机构】 北京有色金属研究总院有色金属制备加工国家重点实验室； 东风汽车公司；

【摘要】 由于汽车工业需要降低尾气排放并降低能源消耗,镁合金成为当前大力开发的轻质结构材料。本文研究了添加不同重量百分比(0 45wt.% 到1.04wt.%)的混合稀土对 AZ91D 压铸镁合金的显微组织和力学性能的影响。在常规冷室压铸条件下,在 AZ91D 镁合金中逐次增加镁基混合稀土中间合金的添加量,压铸了含不同重量百分比混合稀土的镁合金试样。结果表明:尽管在压铸过程中发生不平衡的快速凝固过程,但是随着混合稀土添加量增加,压铸镁合金的显微组织得到细化,并在晶界和晶粒内生成 Al-RE 化合物。稀土元素起到了固溶强化、晶界强化和弥散强化的作用。密度及硬度的测试结果显示由于压铸模具形状及稀土镁合金熔液充型能力的影响在充型过程中形成微小空洞以及组织偏析,严重影响压铸镁合金力学性能.室温和高温下拉伸实验结果表明加入混合稀土改善了 AZ91D 压铸镁合金的常温及高温力学性能。更多还原

【Abstract】 Magnesium alloys are fulfilling the demands for low weight materials that could reduce the emissions of automobile to lower the growing environment impact in automotive industry.The effects of the mischmetal addition ranging from 0.45wt.% to 1.04wt.% on the microstructure and properties of AZ91D alloy prepared by die casting has been investigated in the present paper. Magnesium alloy test bars were produced under well controlled conventional cold chamber die casting condition with addition of different weight of the Mg-MM intermediate alloy.Observation and analysis indicate that the die casting microstructures of the alloy are refined and RE containing Al phase is formed on the condition of rapid solidification. The role of rare earth elements include solid solution hardening,grain boundary hardening and dispersion hardening.The results of hardness and density measurement show that there are a large number of cavities and segregation came into being during solidification process depending on the shape of the mould.The cavity and segregation could damage the mechanical property of the AZ91D magnesium die casting alloys.The data obtained by tensile tests show that alloying with RE improves the tensile property at ambient and elevated temperature.更多还原