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Microstructural Control of Mg_2Ni Hydrogen Absorbing Alloys by Rapid Solidification and Mechanical Grinding

快速凝固和机械研磨对Mg_2Ni吸氢合金的显微组织控制

基本信息

批准号：
09650757
负责人：
KAMADO Shigeharu
金额：
$ 1.79万
依托单位：
NAGAOKA UNIVERSIYT OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

In this study, for improvement in performance of batteries used in electric vehicles, we paid attention to Mg_2Ni protium absorbing alloy that has high protium absorption capacity, lightweight and low price as compared with the existing protium absorbing alloys. But Mg_2Ni alloy has high protium absorption and desorption temperature and slow hydriding kinetics that must be improved for practical purposes.Therefore, for the purpose of decreasing protium absorption and desorption temperature and improving protium absorption rate, we did a partial substitution of Mg_2Ni by third alloying elements. Mn, Fe, Co, Cu, Al, Zn and Ag which are expected to decrease the absolute value of hydride formation enthalpy of Mg_2Ni alloy were selected as third substitutional elements. The ternary alloys were also rapidly solidified, and mechanically ground in order to homogenize their microstructure. The microstructures of specimens obtained by these processes were observed and their protium absorbing and … More desorbing characteristics were investigated. Obtained results are summarized as followed ; (1) All activated specimens absorb protium at room temperature and their protium contents are higher than those of specimens before activation that causes new surface formation and an increase in reaction area. (2) Hydriding kinetics curves measurements show that rapidly solidified specimens of Mg_2Ni_<0.9>Co_<0.1> and Mg2Ni_<0.9>Fe_<0.1> alloys have the highest reaction rate. It is considered that Fe and Co substitution accelerated the diffusion of protium in these two alloys and rapid solidification cause the fine microstructure. (3) As the elapsed time after taking specimens out from hydrogen atmosphere increases, the protium desorption temperature decreases and desorbed protium contents increases. Microstmctural changes of the hydride from high temperature phase to low temperature phase probably causes this phenomenon. Similar results can be obtained when manually hydride of manually ground specimens after activation shows the same microstructural change, resulting in improvement of the desorption characteristics. (4) By addition of third alloying elements and Ni substitution, both activation energy and enthalpy for dehydriding decreases.From the above results, rapid solidification, mechanical grinding and substitution by 3d transition metals for Ni site in Mg_2Ni crystal structure are effective for improving the protium absorbing and desorbing characteristics of Mg_2Ni alloy. Less

在本研究中，为了提高电动汽车用电池的性能，我们关注的是与现有的吸收合金相比，具有高吸收容量、重量轻、价格低的镁镍吸收合金。但由于镁镍合金具有较高的锶吸脱附温度和较慢的吸放氢动力学，因此，为了降低锶的吸脱附温度，提高锶的吸收率，我们用第三合金元素对镁镍合金进行了部分替代。选择有望降低镁镍合金氢化物生成热绝对值的Mn、Fe、Co、Cu、Al、Zn、Ag等元素作为第三替代元素。还对三元合金进行了快速凝固和机械研磨，以使其组织均匀。观察了这几种工艺制备的样品的微观结构，并对其进行了吸钚和…分析。考察了更多的解吸特性。主要研究结果如下：(1)活化后的样品在室温下都吸附了钚，其含量高于活化前的样品，形成了新的表面，增加了反应面积。(2)吸氢动力学曲线测试表明，快速凝固的Mg_2Ni_t；0.9&gt；Co_&lt；0.1&gt；和Mg_2Ni_&lt；0.9&gt；Fe_&lt；0.1&gt；合金具有最高的反应速率。认为Fe、Co替代促进了两种合金中Pr的扩散，快速凝固形成了细小的显微组织。(3)随着样品从氢气氛中取出后时间的增加，脱附温度降低，脱附的含量增加。这可能是氢化物由高温相向低温相转变的微观结构变化所致。人工氢化处理的样品经活化处理后，其微观结构也发生了相同的变化，从而改善了脱附特性。(4)添加第三合金化元素和Ni替代后，合金的脱氢活化能和脱放热都有所降低，快速凝固、机械研磨和用3D过渡金属取代Mg_2Ni晶体结构中的Ni位是改善Mg_2Ni合金吸、放钚性能的有效方法。较少