Mg-Cu-Nd贮氢合金的微观组织结构及贮氢性能研究

Microstructure and Hydrogen-Storage Property for Mg-Cu-Nd Alloy

采用熔体快淬法制备了(Mg72.2Cu27.8)90Nd10的非晶贮氢合金带,用DSC差热分析仪测定了非晶合金带的热稳定性和非晶形成能力,采用透射电镜TEM和X射线衍射仪表征了不同结晶程度的贮氢合金带的微观组织结构。结果表明:非晶(Mg72.2Cu27.8)90Nd10贮氢合金的晶化过程分为3个步骤:首先在170℃生成平均晶粒尺寸为5～10 nmMg2Cu相;当回火处理温度升高至210℃时,非晶(Mg72.2Cu27.8)90Nd10贮氢合金发生了第二步晶化反应,生成了α-Mg相;当回火处理温度升高到335℃以后,非晶贮氢合金已经完全晶化,生成了稳定的Mg2Cu,α-Mg和Cu5Nd相,晶化后的颗粒尺寸有50～80 nm。对不同组织结构的(Mg72.2Cu27.8)90Nd10合金的贮氢性能测试表明:完全非晶状态的(Mg72.2Cu27.8)90Nd10合金具有最快的吸氢速率和最高的贮氢量(3.2%(质量分数))。

Amorphous Mg-based alloy（Mg72.2Cu27.8）90Nd10 was prepared by melt spinning.The thermal stability and phase transition in the as-quenched alloy were studied by TEM,DSC,X-ray and electron diffraction.It was found that the crystallization process of melt-spun（Mg72.2Cu27.8）90Nd10 ribbons consisted of three steps.The first crystallization reaction at about 170 ℃ was connected with the formation of Mg2Cu nanocrystalline phase with average grain size in the range 5~10 nm,followed by formation of a coarser grained α-Mg crystalline phase（210 ℃） corresponding to a second crystallization reaction.At higher temperatures a third exothermic effect（at about 335 ℃） could be detected and the stable Mg2Cu,α-Mg and Cu5Nd phases were present with the biggest grain size about 50~80 nm.The hydrogenation characteristics of the as-quenched and the annealed samples（partially and fully crystallized） were compared as well.The amorphous（Mg72.2Cu27.8）90Nd10 alloy showed the best initial hydrogenation rate and the maximum hydrogen capacity（3.2%） in comparison with those of partially crystalline and completely crystallized microstructural states.