Zr1-xCoNbx (x = 0-0.2)合金吸放氢性能及抗歧化机制研究

采用真空电弧熔炼法制备了Zr_1-xCoNb_x (x = 0,0.05,0.1,0.15,0.2)合金,研究了Nb掺杂对合金晶体结构、吸放氢及抗歧化性能的影响。XRD结果表明：Zr_1-xCoNb_x (x = 0-0.2)合金主相为ZrCo相,含有少量ZrCo₂杂相；其氢化物为ZrCoH₃和ZrCo₂相。Nb掺杂极大地提高了合金吸氢动力学性能,ZrCo吸氢反应活化时间为7690 s,Zr_0.8CoNb_0.2缩短至380 s。ZrCo吸氢反应活化能为44.88 kJ mol^_-1 H₂,Zr_0.8CoNb_0.2降低至32.73 kJ mol^_-1 H₂,有利于吸氢反应动力学性能。DSC测量结果表明：ZrCo放氢温度为597.15 K,Zr_0.8CoNb_0.2降低至541.36 K,放氢温度降低,有利于抗歧化性能。ZrCo合金放氢反应活化能为100.55 kJ mol^_-1 H₂,Zr_0.8CoNb_0.2降低至84.58 kJ mol^_-1 H₂。合金歧化程度随着Nb掺杂量增加而降低,798 K保温10 h,ZrCo歧化83.68%,Zr_0.8CoNb_0.2仅歧化8.71%,Nb掺杂降低8f₂和8e位置氢原子数量,减小岐化反应驱动力。

Study on the Improvement of Hydrogen Absorb/desorb Properties and Anti-disproportionation performance of Zr1-XCoNbx (x = 0-0.2) alloys

Zr_1-xCoNb_x (x = 0, 0.05, 0.1, 0.15, 0.2) alloys were prepared via vacuum arc-melting method. The effects of substituting Zr with Nb on the structure, hydrogen absorb/desorb properties and anti-disproportionation performance of the afore-mentioned alloys were systematically investigated. The results showed that Zr_1-xCoNb_x (x = 0-0.2) alloys exhibited ZrCo and ZrCo₂ phases, and their corresponding hydrides consisted of ZrCoH₃ and ZrCo₂ phase. As the Nb content was increased, the activation time decreased significantly from 6790 s for ZrCo to 380 s for Zr_0.8CoNb_0.2. The activation energy for hydrogenation decreased from 44.88 kJ mol^_-1 H₂ for ZrCo to 32.73 kJ mol^_-1 H₂ for Zr_0.8CoNb_0.2 alloy. DSC measurement results showed that the desorption temperature decreased from 597.15 K for ZrCo to 541.36 K for Zr_0.8CoNb_0.2 and the activation energy for dehydrogenation decreased from 100.55 kJ mol^_-1 H₂ for ZrCo to 84.58 kJ mol^_-1 H₂ for Zr_0.8CoNb_0.2 alloy, which was beneficial to the anti-disproportionation properties. Additionally, the extents of disproportionation of alloys after disproportionated at 798 K for 10 h decreased from 83.68% for ZrCo to 8.71% for Zr_0.8CoNb_0.2. The positive effect of Nb substitution on improving the anti-disproportionation propertis of ZrCo alloys was attributed to the reduction of hydrogen atoms in 8f₂ and 8e sites, which decreases the driving force of the disproportionation reaction.