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为了改善Mg2Ni型合金的电化学贮氢性能,用La部分替代Mg,并用铸造及快淬工艺制备了Mg2-xLaxNi(x=0、0.2、0.4、0.6)贮氢合金。用XRD、SEM、HRTEM分析了铸态及快淬态合金的微观结构,用程控电池测试仪测试了合金的电化学贮氢性能,研究了快淬工艺对合金结构及电化学性能的影响。结果发现,La替代Mg明显地改变Mg2Ni型合金的相组成。当x≤0.2时,La替代Mg不改变合金的主相Mg2Ni,但出现少量的LaMg3及La2Mg17相;当La替代量x≥0.4时,合金的主相改变为(La,Mg)Ni3+LaMg3相。La替代Mg提高了Mg2Ni合金的非晶形成能力,快淬态合金均具有明显的纳米晶/非晶结构。快淬对合金电化学性能的影响与合金的成分相关,快淬显著地提高了Mg1.8La0.2Ni合金的电化学贮氢性能,但对于Mg1.4La0.6Ni合金,快淬导致了完全相反的结果,这主要与La替代使合金的主相发生改变相关。
In order to improve the electrochemical hydrogen storage properties of Mg2Ni alloy, part of La was substituted for Mg, and Mg2-xLaxNi (x = 0,0.2,0.4,0.6) hydrogen storage alloys were prepared by casting and rapid quenching. The microstructures of as-cast and quenched alloys were analyzed by XRD, SEM and HRTEM. The electrochemical hydrogen storage properties of the alloys were tested by a programmed cell tester. The effects of quenching process on the structure and electrochemical properties of the alloys were investigated. As a result, it was found that La substitution for Mg significantly changed the phase composition of the Mg2Ni-type alloy. When x≤0.2, La substitutional Mg did not change the main phase Mg2Ni, but a small amount of LaMg3 and La2Mg17 phases appeared. When La substitutional amount x≥0.4, the main phase of the alloy changed to (La, Mg) Ni3 + LaMg3 . The substitution of Mg for La improves the amorphous formation ability of Mg2Ni alloy, and the quenched alloys have obvious nanocrystalline / amorphous structure. The effect of quenching on the electrochemical properties of the alloy is related to the composition of the alloy. Quenching significantly increases the electrochemical hydrogen storage capacity of the Mg1.8La0.2Ni alloy, however, for Mg1.4La0.6Ni alloy, quenching leads to the opposite As a result, this is mainly related to the substitution of La for the major phase of the alloy.