共查询到19条相似文献,搜索用时 125 毫秒
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纯镍中杂质元素As,Sb ,Pb ,Sn ,Bi等的含量对其本身的性能和由其冶炼的合金的性能有着很大的影响 ,因此准确测定纯镍中这些杂质元素的含量具有重要意义。采用空心阴极光谱法测定纯镍中杂质元素的含量具有灵敏度高、稳定性好、用料少等优点 ,由于不需要经过化学处理 ,减少了被污染的机会。试验方法为称取金属颗粒样品 ,装入石墨电极中 ,在光栅光谱仪上 ,以空心阴极光源为激发源 ,在氩气气氛中进行放电 ,经光栅摄谱仪分光成像后 ,记录于感光板上 ,在测微光度计上测出待测元素的谱线黑度 ,在工作曲线上查得待测元素的百分含量。试样… 相似文献
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为评价低温土壤对镁合金阳极电化学性能的影响,通过极化曲线、交流阻抗和电流效率实验方法,研究了4种镁合金阳极在-4℃和4℃的模拟低温青藏高原土壤中的电化学性能.研究表明:镁合金中加入Mn、Al和Zn元素可与杂质元素形成阴极作用较弱的金属间化合物,降低了镁合金的自溶解倾向,提高了电流效率;镁合金阳极在低温青藏高原土壤中呈活性溶解状态,溶解活性和反应活性由强到弱顺序为MGAZ63B镁合金、MGAZ31B镁合金、MGM1C镁合金和高纯镁;4种镁合金阳极中MGAZ63B的电流效率最高,-4℃和4℃时分别为54.39%和61.77%;4℃土壤中氧的扩散速率比-4℃时高,故镁合金阳极在青藏高原土壤中4℃时溶解活性和电流效率均优于-4℃时. 相似文献
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镁及其合金作为最轻的金属结构材料,在产品轻量化方面具有巨大的应用潜力.然而,金属镁具有较强的腐蚀敏感性,且表面形成的氢氧化镁膜疏松多孔,几乎无保护性,这导致其应用受到限制.如何提高镁的耐腐蚀性已经成为制约其应用的世界性难题.合金化是从根本上改善镁合金耐蚀性的方法之一.基于此,本文从合金元素对镁腐蚀行为的影响出发,阐述纯镁的腐蚀机理和合金元素对镁合金腐蚀性能的影响机制,归纳合金元素对镁合金所产生的保护机制及其相应特征,这可以为开发新型镁合金和改善镁合金的耐蚀性提供一定的借鉴.此外,本文有助于更好地理解镁合金腐蚀行为.目前,还没有一种镁合金能像铝合金或不锈钢一样具有较好的耐蚀性,因此耐蚀镁合金的开发还需要进一步研究.本文为镁合金中元素之间的交互关系提供理论基础,可对新型耐蚀镁合金的开发提供思路.元素之间的协同作用会对新型耐蚀镁合金设计、工艺及性能有较大影响,随着研究的深入,期望构建出类似"不锈钢"的新型耐蚀镁合金. 相似文献
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Xianhua Chen Fusheng Pan Jianjun Mao Jiansheng Huang 《Journal of Materials Science》2012,47(1):514-520
The effect of impurity reduction on the hot rolling behavior of AZ31 magnesium alloy was systematically investigated in this
study. In the as-cast alloys, the total content of main impurity elements such as Fe, Si, Cu, and Ni was varied from 0.0462
to 0.0163 wt% by changing the purity of used raw magnesium metals. The alloys after homogenization were subjected to hot rolling
at 300 °C with a reduction of 20% per pass. It was found that the initiation of edge cracks is postponed with reducing impurity
level in the alloys. And the maximum rolling reduction prior to edge cracking increases from 34 to 58% as the impurity content
drops from 0.0462 to 0.0163 wt%. Microstructural observations showed that smaller grains are present in the alloy with lower
impurity content in the cast and homogenization states. Moreover, decreasing impurity content leads to a reduced number of
deformation twins and an enhanced volume fraction of small recrystallized grains in the as-rolled microstructure, which indicates
that impurity reduction is beneficial to the recrystallization process and subsequent plastic deformation. Based on the results,
the enhancement in hot rollability of the AZ31 sheet by impurity reduction should be due to finer grain size, the reduced
number of deformation twins and the enhanced extent of recrystallization. 相似文献
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AbstractIn this paper, the possibility of removing impurities during magnesium recycling with pyrometallurgical techniques has been evaluated by using a thermodynamic analysis. For 25 different elements that are likely to be contained in industrial magnesium alloys, the equilibrium distribution ratios between the metal, slag and gas phases in the magnesium remelting process were calculated assuming binary systems of magnesium and an impurity element. It was found that calcium, gadolinium, lithium, ytterbium and yttrium can be removed from the remelted end-of-life (EoL) magnesium products by oxidization. Calcium, cerium, gadolinium, lanthanum, lithium, plutonium, sodium, strontium and yttrium can be removed by chlorination with a salt flux. However, the other elements contained in magnesium alloy scrap are scarcely removed and this may contribute toward future contamination problems. The third technological option for the recycling of EoL magnesium products is magnesium recovery by a distillation process. Based on thermodynamic considerations, it is predicted that high-purity magnesium can be recovered through distillation because of its high vapor pressure, yet there is a limit on recoverability that depends on the equilibrium vapor pressure of the alloying elements and the large energy consumption. Therefore, the sustainable recycling of EoL magnesium products should be an important consideration in the design of advanced magnesium alloys or the development of new refining processes. 相似文献
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In traditional alloy development, experimental investigations with many different alloy compositions are performed. The selection criteria for multicomponent alloying elements and their compositions become diffuse in a traditional approach. Computational thermochemistry as used in the Calphad approach can provide a clear guideline for such selections and helps to avoid large scale experiments with less promising alloys. Thus, it is a powerful tool to cut down on cost and time during development of Mg‐alloys. An overview of the Calphad method is given. As an example of applications, recent developments of new creep resistant magnesium alloys that show about 100 times less creep than the best commercial alloys are reported. Also outlined are the methods used in our long‐term project of construction of the necessary thermodynamic magnesium alloy database for several alloying elements, such as Al, Li, Si, Mn, Ca, Sc, Y, and Zr, and rare earth elements (Ce, Gd, Nd), using the Calphad method combined with key experiments. 相似文献
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J. N. Li P. Cao X. N. Zhang S. X. Zhang Y. H. He 《Journal of Materials Science》2010,45(22):6038-6045
Currently available engineering magnesium alloys have several critical concerns if they are about to be used as biomaterials,
particularly the concern about the toxicity of the common alloying elements such as aluminum and rare earth (RE). There is
an increasing demand to develop new magnesium alloys that do not contain any toxic elements. It is also desirable, yet challenging,
to develop such a material that has a controllable degradation rate in the human fluid environment. This paper presents mechanical
properties, degradation, and in vitro cell attachment of a newly developed Mg–6Zn magnesium alloy. The alloy demonstrated
comparable mechanical properties with typical engineering magnesium alloys. However, the bare alloy did not show an acceptable
corrosion (degradation) rate. Application of a polymeric PLGA or poly(lactide-co-glycolide) coating significantly decreased the degradation rate. The results obtained from cell attachment experiments indicated
that the mouse osteoblast-like MC3T3 cells could develop enhanced confluence on and interactions with the coated samples. 相似文献
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