Mg_(67-x)Ca_xNi_(33)(x=0,5,10,15,20,at%)合金的物相及储氢性能研究

Study of Phase Composition and Hydrogen Storage Properties of Mg_(67-x)Ca_xNi_(33)(x=0,5,10,15,20,at%) Alloys

采用感应熔炼、甩带结合机械球磨法制备了Mg67-xCaxNi33(x=0,5,10,15,20,at%)储氢合金。研究了Ca含量及制备工艺对合金相结构和储氢性能的影响。结果表明,制备工艺(熔炼,熔炼+球磨,熔炼+甩带+球磨)对储氢合金的物相组成影响不大,而含Ca的合金经过甩带后容易形成非晶。不含Ca的Mg67Ni33合金主要由Mg2Ni相组成,并含有少量的Mg相;随着Ca含量升高,合金中的Mg2Ni相逐渐减少,而MgNi2相和Mg2Ca相逐渐增加。当Ca含量增加到20at%时,Mg47Ca20Ni33则主要由MgNi2和Mg2Ca组成,几乎没有Mg2Ni生成。P-C-T测试结果表明,在573K下,Mg67-xCaxNi33合金的最大吸氢量随着合金中Ca含量的升高而降低,这主要是由于Mg2Ni相含量减少造成的。吸氢后的Mg67Ni33主要由Mg2NiH4组成,而含Ca合金吸氢后则主要由Mg2NiH4、CaH2和不吸氢的MgNi2相组成。

Mg-based hydrogen storage alloys Mg67-xCaxNi33 （x=0, 5, 10, 15, 20, at%） were prepared by means of induction melting, melt-spinning and ball milling. The effects of Ca content and preparation technologies on phase composition and hydrogen storage properties were studied. The results show that the preparation technologies （as-cast, casting ＋ ball milling and casting ＋ melt-spinning ＋ ball milling） have little effect on the phase composition. The alloys containing Ca can form amorphous after melt-spinning. Mg67Ni33 alloy are mainly composed of Mg2Ni and a little quantity of Mg. The content of Mg2Ni decreases, while MgNiz and Mg2Ca increase with the increase of Ca content in Mg67-xCaxNi33 alloys. When Ca content reaches 20at%, MgaTCa20Ni33 alloy mainly consist of MgNi2 and Mg2Ca phase. P-C-T tests show that the maximum hydrogen storage capacity of Mg67-xCaxNi33 alloys decreases with increase of Ca content due to the decrease of MgaNi phase. After hydrogen absorption, Mg67Ni33 consists of MgzNiH4 phase, while Ca containing alloys Mg67-xCaxNi33 alloys consist of Mg2NiH4, CaH2 and MgNi2.