[摘　　要]：

在300～400℃和较高压力下，镁与氢反应生成MgH2。但MgH2稳定性强，释氢困难，分解温度过高。为了克服镁的这些缺点，本文对Mg3RE合金进行了研究，并在此基础上开发三元、四元合金。本文采用感应熔炼法制备了一系列的Mg-RE基储氢合金，研究了添加Ni元素对各Mg3RE合金微观组织结构及相应的氢化、脱氢过程中相变的影响，通过测量Mg3RE和Mg3RENi0.1合金的PCI曲线，探讨了Ni对Mg3RE合金热力学和动力学特性的影响，并对合金氢化后的水解反应做了初步探讨。 研究结果表明，Mg3RE合金都为D03结构（BiF3型，空间群Fm3m）的Mg3RE相。从Mg3La、Mg3Ce、Mg3Pr到Mg3Nd，随着La、Ce、Pr和Nd的原子半......更多

在300～400℃和较高压力下，镁与氢反应生成MgH2。但MgH2稳定性强，释氢困难，分解温度过高。为了克服镁的这些缺点，本文对Mg3RE合金进行了研究，并在此基础上开发三元、四元合金。本文采用感应熔炼法制备了一系列的Mg-RE基储氢合金，研究了添加Ni元素对各Mg3RE合金微观组织结构及相应的氢化、脱氢过程中相变的影响，通过测量Mg3RE和Mg3RENi0.1合金的PCI曲线，探讨了Ni对Mg3RE合金热力学和动力学特性的影响，并对合金氢化后的水解反应做了初步探讨。 研究结果表明，Mg3RE合金都为D03结构（BiF3型，空间群Fm3m）的Mg3RE相。从Mg3La、Mg3Ce、Mg3Pr到Mg3Nd，随着La、Ce、Pr和Nd的原子半径的减小，所对应的Mg3RE相的晶格常数逐渐减小。添加催化元素Ni后，Mg3RENi0.1合金中形成MgAl2Cu型结构的第二相，即REMg2Ni相（但在Mg3CeNi0.1合金中新形成相为Ce2Mg17）。Mg3RE合金在第一次氢化后，发生歧化，转变为MgH2相和REH2～3相，氢化物脱氢后MgH2相分解为Mg单质和氢气，REH2～3相不发生结构上的改变。XRD测试表明加Ni后形成的新相REMg2Ni相并没有和氢气直接反应生成REMg2NiH7。 PCI曲线测试分析表明，Mg3RE合金中，Mg3La合金的吸氢量最高，吸氢平台最宽，Mg3Nd合金的吸氢量最低，吸氢平台也最窄，Mg3Ce、Mg3Pr和Mg3Mm合金吸氢性能介于Mg3La和Mg3Nd合金之间。在添加催化元素Ni后，Mg3LaNi0.1和Mg3MmNi0.1合金的吸氢量有所减少，Mg3CeNi0.1、Mg3PrNi0.1和Mg3NdNi0.1合金的吸氢量却有较大提高。添加Ni元素后，各Mg3RENi0.1合金的放氢温度都有所降低。 动力学性能分析结果表明，Mg3RE合金的吸氢过程都满足形核长大机制，其中Mg3Nd合金的吸氢动力学性能最好，其次为Mg3La、Mg3Mm和Mg3Ce合金，Mg3Pr合金的吸氢动力学性能最差。添加Ni元素后，Mg3LaNi0.1、Mg3CeNi0.1和Mg3PrNi0.1合金的吸氢速率要快于相应的Mg3RE合金。Mg3LaNi0.1、Mg3CeNi0.1和Mg3NdNi0.1合金的氢化过程满足形核长大机制，Mg3PrNi0.1合金的氢化过程为自催化反应机制。 氢化后的Mg-La系合金能与水反应放出氢气，水解放氢过程满足成核长大机制，放氢速率取决于合金中La的含量。添加Al、Co、Mn元素，氢化后的样品水解放氢动力学性能得到一定的改善，放氢量也有所提高。Mg3RENi0.1合金中，Mg3PrNi0.1合金氢化后水解放氢动力学性能最好，Mg3LaNi0.1合金氢化后的水解放氢动力学性能最差，Mg3NdNi0.1和Mg3CeNi0.1合金的介于两者之间。整个水解过程都是自发进行，过程中没有外部能量输入，水解产物主要由La(OH)3 和Mg(OH)2构成。关闭

At 300~400℃ and high pressure, the reaction product between magnesium and hydrogen is MgH2. However, the stability and decomposition temperature of MgH2 are too high to release hydrogen. In order to overcome these shortcomings, Mg-RE (RE=La, Ce, Pr, Nd and Mm) alloys have been developed. In this paper, we studied the effects of Ni addition on the microstructure, phase transformation, thermokinetics and kinetics properties in the hydriding/dehydriding process of Mg3RE alloys prepared by induction melting. The behavior and preliminary ......更多

At 300~400℃ and high pressure, the reaction product between magnesium and hydrogen is MgH2. However, the stability and decomposition temperature of MgH2 are too high to release hydrogen. In order to overcome these shortcomings, Mg-RE (RE=La, Ce, Pr, Nd and Mm) alloys have been developed. In this paper, we studied the effects of Ni addition on the microstructure, phase transformation, thermokinetics and kinetics properties in the hydriding/dehydriding process of Mg3RE alloys prepared by induction melting. The behavior and preliminary research on the reaction mechanism of hydrolysis was also made. The research results show that the structure of Mg3RE alloys is D03 structured CeMg3 phase (BiF3 type，Space group Fm3m). The lattice constants of Mg3La, Mg3Ce, Mg3Pr and Mg3Nd decrease gradually with reducing of atom radius of La, Ce, Pr and Nd. After adding the catalytic element Ni to get Mg3RENi0.1 alloys, the structure was changed, and REMg2Ni phase in the alloy formed (for Mg3CeNi0.1 alloy, the new phase is Ce2Mg17 phase). The structure of Mg3RE alloys transforms to MgH2 and REH2~3 phase after the first absorption, and in dehydrogenation process MgH2 phase decomposed into pure Mg and H2, while the structure of REH2~3 phase remains unchanged. There was no REMg2NiH7 phase by reaction between REMg2Ni phase and hydrogen after adding Ni. PCI curves analysis showed that the Mg3La alloy had the highest absorption capacity, the widest platform, and Mg3Nd alloy had the lowest absorption capacity, the narrowest platform among Mg3RE alloys. After adding element Ni, absorption capacity of Mg3LaNi0.1 and Mg3MmNi0.1 alloys reduced, but absorption capacity of Mg3CeNi0.1, Mg3PrNi0.1 and Mg3NdNi0.1 alloys improved greatly. The dehydriding temperature of Mg3RENi0.1 alloys reduced after adding element Ni. The kinetic analysis showed that Mg3Nd alloy had the best hydriding kinetics properties, followed by Mg3La, Mg3Mm and Mg3Ce alloys, while Mg3Pr alloy had the worst hydriding kinetics properties. The hydriding reaction process of Mg3RE alloys were controlled by nucleation and growth mechanism. After adding element Ni, the hydriding reaction rate of Mg3LaNi0.1, Mg3CeNi0.1 and Mg3PrNi0.1 alloys were faster than the corresponding Mg3RE alloys. The hydriding reaction process of Mg3LaNi0.1, Mg3CeNi0.1 and Mg3NdNi0.1 alloys fit well with the nucleation and growth mechanism, but that of Mg3PrNi0.1 alloy was autocatalytic reaction mechanism. Hydrogenated Mg-La alloys can react with water and release hydrogen, and the hydrolytic process fit well with the nucleation and growth mechanism. Hydrolytic rate depended on the content of La in alloys. The hydrolytic kinetic properties of the hydrogenated samples improved and the amount of hydrogen production also increased after adding element Al, Co or Mn. Mg3PrNi0.1 alloy had the best hydrolytic kinetic properties. However, Mg3LaNi0.1 alloy had the worst hydrolytic kinetic properties among Mg3RENi0.1 alloys. The hydrolytic kinetic properties of Mg3NdNi0.1 and Mg3CeNi0.1 alloys were between the two alloys mentioned above. The hydrolytic process carried on spontaneously without external energy, the hydrolytic products are La(OH)3 and Mg(OH)2.关闭