Co替代Ni对快淬Mg2Ni型合金结构及 电化学贮氢性能的影响

来源期刊:中国有色金属学报2011年第1期

论文作者:张羊换 马志鸿 赵栋梁 张胤 郭世海 王新林

文章页码:118 - 124

关键词:Mg2Ni型合金;快淬;Co替代Ni;电化学贮氢

Key words:Mg2Ni-type alloy; melt-spinning; substituting Ni with Co; electrochemical hydrogen storage

摘    要:为了改善Mg2Ni型贮氢合金的电化学贮氢性能,以Co部分替代合金中的Ni,用快淬工艺制备Mg2Ni型Mg2Ni1-xCox (x = 0, 0.1, 0.2, 0.3, 0.4)合金, 获得长度连续、厚度约为30 μm、宽度约为25 mm的快淬合金薄带。并用XRD、SEM、HRTEM分析快淬态合金薄带的微观结构;用DSC研究快淬薄带的热稳定性;用程控电池测试仪测定合金薄带的电化学贮氢性能;探索Co替代Ni对快淬Mg2Ni型合金结构及电化学贮氢性能的影响。结果表明:在快淬无Co合金中没有发现非晶相,但快淬含Co合金中存在明显的非晶结构,证明Co替代Ni提高了Mg2Ni型合金的非晶形成能力。Co替代Ni使快淬态合金的热稳定性略有提高,显著地改善了合金的电化学贮氢性能,包括放电容量、电化学循环稳定性以及高倍率放电性能,这主要归因于Co替代Ni导致结构的变化以及非晶形成能力的提高。

Abstract: In order to improve the electrochemical hydrogen storage characteristics of the Mg2Ni-type alloy, Ni in the alloy was partially substituted by element Co. The Mg2Ni-type Mg2Ni1-xCox (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were prepared by melt-spinning technology. The spun ribbons with a continuous length, a thickness of about 30 μm and a width of about 25 mm were obtained. The microstructures of the spun alloy ribbons were analyzed by XRD, SEM and HRTEM. The thermal stability of the as-spun alloys was investigated by DSC. The electrochemical hydrogen storage performances of the spun alloy ribbons were tested by an automatic galvanostatic system. The influences of substituting Ni with Co on the structure and electrochemical hydrogen storage characteristics of melt spun Mg2Ni-type alloy were investigated. The results show that no amorphous phase is detected in the as-spun Co-free alloy, but the as-spun alloys containing Co display an evident percent of amorphous phase, suggesting that the substitution of Co for Ni significantly heightens the glass forming ability of the Mg2Ni-type alloy. The substitution of Co for Ni causes a slight increase in the thermal stability of the as-spun alloy, and significantly improves the electrochemical hydrogen storage performances of the alloys, involving the discharge capacity and the cycle stability as well as the high rate discharge (HRD) capability, for which the increased glass forming ability by Co substitution is mainly responsible.

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