稀土元素Nd对ZM6镁合金力学性能的影响
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摘要
笔者主要研究稀土元素Nd对ZM6镁合金力学性能的影响,通过浇筑不同Nd含量的ZM6试棒及显微组织腐蚀试样来研究其显微组织、成分分析,找出镁合金在室温下最高抗拉强度时的Nd含量。Nd可在一定程度上细化ZM6合金组织,且热处理后的细化效果与铸态相近,但热处理后出现了富锌相颗粒,随Nd含量的增加,富锌相颗粒尺寸增大。试验结果表明,局部基体Nd、Zr、Zn的含量极低,Mg的含量几乎是百分之百,加入的合金元素主要集中在晶界上,从成分分析以及Mg的相图来看,晶界上的析出物为Mg、Nd、Zn组成的Mg_(12)(Nd,Zn)相。热处理能改善ZM6合金晶界状态,使Nd元素在组织内弥敞分布,从而提高晶界强度,使合金性能提高。ZM6合金的硬度随着Nd含量的增加而增加。随着Nd含量的增加,合金的室温抗拉强度增加。当Nd含量超过3.0%时,ZM6镁合金的室温拉伸强度有下降趋势。
In this paper, the effect of rare earth element Nd on the mechanical properties of ZM6 magnesium alloy was studied. The microstructure and composition of ZM6 magnesium alloy were studied by pouring different Nd content of ZM6 test rod and microstructure corrosion specimen. It was found that the microstructure of ZM6 alloy could be refined to some extent at the highest tensile strength of magnesium alloy at room temperature, and the refining effect after heat treatment was similar to that of as-cast alloy, but the zinc-rich phase particles appeared after heat treatment, which increased with the increase of Nd content. The particle size of zinc-rich phase is increased. The results show that the content of Zn in local matrix is very low, the content of mg is almost 100%, and the alloy is added. The elements are mainly concentrated on grain boundaries. From the composition analysis and the phase diagram of mg, the precipitates on the grain boundaries are Mg_(12)(NdZn-Zn) phases. Heat treatment can improve the grain boundary state of ZM6 alloys and make Nd elements distribute in the microstructure, thus increasing the strength of grain boundaries. The hardness of ZM6 alloy increases with the increase of Nd content, and the tensile strength at room temperature increases with the increase of Nd content. The tensile strength of ZM6 magnesium alloy decreases at room temperature when Nd content exceeds 3.0.
In this paper, the effect of rare earth element Nd on the mechanical properties of ZM6 magnesium alloy was studied. The microstructure and composition of ZM6 magnesium alloy were studied by pouring different Nd content of ZM6 test rod and microstructure corrosion specimen. It was found that the microstructure of ZM6 alloy could be refined to some extent at the highest tensile strength of magnesium alloy at room temperature, and the refining effect after heat treatment was similar to that of as-cast alloy, but the zinc-rich phase particles appeared after heat treatment, which increased with the increase of Nd content. The particle size of zinc-rich phase is increased. The results show that the content of Zn in local matrix is very low, the content of mg is almost 100%, and the alloy is added. The elements are mainly concentrated on grain boundaries. From the composition analysis and the phase diagram of mg, the precipitates on the grain boundaries are Mg_(12)(NdZn-Zn) phases. Heat treatment can improve the grain boundary state of ZM6 alloys and make Nd elements distribute in the microstructure, thus increasing the strength of grain boundaries. The hardness of ZM6 alloy increases with the increase of Nd content, and the tensile strength at room temperature increases with the increase of Nd content. The tensile strength of ZM6 magnesium alloy decreases at room temperature when Nd content exceeds 3.0.
引文
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2 Kim H K,Kim W J.Microstructural instability and strength of an AZ31 Mg alloy after severe plastic deformation. Materials Science and Engineering,2004,303(289):300～308
3 Yoshida Yu,Arai Keita,Itoh Shota,et al.Realization of high strength and high ductility for AZ61 magnesium alloy by severe warm working.Science and Technology of Advanced Materials,2005,23(6):185～194
4 Jayamathy M,Kailas S V,Kumar K,et al.The compressive deformation and impactresponse of a magnesium alloy: influence of reinforcement.Materials Science and Engineering,2005,304(212):112～120
5 张诗昌,段汉桥,蔡启舟,等.主要合金元素对镁合金组织和性能的影响.铸造,2001,27(6):310～315
6 郑来苏,刘忠元,季玮,等.铸造合金及其熔炼.西安:西北工业大学出版社,1994
7 Von Buch F,Lietzau J,et al.Development of Mg-Sc-Mn Alloys. Materials Science and Engineering,1999,296(212):1～7
8 You B S,Park W W,et al.The Effect of Calcium Additions on the Oxidation Behavior in Magnesium Alloys.Scripta Mater,2000,212(42):1 089～1 094
9 Kim Jae Joong,Kim Do Hyang,et al.Modification of Mg2Si morphology squeeze cast Mg-Al-Zn-Si alloys by Ca or P addition.Scripta Mater,1999,41(3):333～340
10 Nie J F,Muddle B C.Precipitation in magnesium alloy WE54 during isothermal ageing at 250 ℃.Scripta Mater,2007,40(10):1 089～1 094
11 Hassan S F,Gupta M.Development of a novel magnesium/nickel composite with improved mechanical properties.Journal of Alloys and Compounds,2002,335(22):10～15