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采用熔体快淬法制备了(Mg70.6Ni29.4)90Nd10的非晶贮氢合金带,用X射线衍射仪和高分辨电镜对该合金在充放电循环过程中的组织结构演变进行了动态跟踪。结果表明:非晶(Mg70.6Ni29.4)90Nd10贮氢合金在充放电循环过程中经过4个循环以后开始晶化,首先生成平均颗粒尺寸为5 nm左右的NdMg2Ni9相,经过6个循环以后开始出现Mg2Ni相,到第20个循环后,生成了稳定的Mg2Ni,α-Mg和Nd2H5相。这表明初生相NdMg2Ni9在充放电循环过程中逐渐转化为Mg2Ni,α-Mg和Nd2H5相。经过热力学计算进一步验证表明,非晶(Mg70.6Ni29.4)90Nd10合金在晶化过程中首先形成NdMg2Ni9相,因为它的自由能(ΔG=-15.2789 kJ.mol-1,T=300 K)与Mg-Ni相(ΔG=-8.2694 kJ.mol-1,T=300 K)和Mg-Nd相(ΔG=-13.29503 kJ.mol-1,T=300 K)相比是最低的。
The amorphous hydrogen storage alloy tape (Mg70.6Ni29.4) 90Nd10 was prepared by melt quenching method. The microstructure of the alloy was dynamically tracked by X-ray diffraction and high-resolution electron microscopy during the charge-discharge cycles . The results show that the amorphous (Mg70.6Ni29.4) 90Nd10 hydrogen storage alloy begins to crystallize after 4 cycles of charging and discharging cycles, and the NdMg2Ni9 phase with the average particle size of about 5 nm is formed. After 6 cycles Mg2Ni phase appears, and after the 20th cycle, stable Mg2Ni, α-Mg and Nd2H5 phases are formed. This shows that the primary phase NdMg2Ni9 gradually transformed into Mg2Ni, α-Mg and Nd2H5 phases during the charge-discharge cycle. Further verification by thermodynamic calculation shows that NdMg2Ni9 phase is first formed in the amorphous (Mg70.6Ni29.4) 90Nd10 alloy because of its free energy (ΔG = -15.2789 kJ · mol-1, T = 300 K) The Mg-Ni phase (ΔG = -8.2694 kJ.mol-1, T = 300 K) is the lowest compared to the Mg-Nd phase (ΔG = -13.29503 kJ.mol-1, T = 300 K).