Mo含量对Ti-Mo合金氢同位素效应的影响

采用磁悬浮熔炼法制备了固溶体合金TiMox（x=0．03、0．13、0．25、0．50、1．00，x为Mo与Ti原子数之比），经活化后与H—D混合气（D原子占50％）反应，反应平衡后用质谱分析气相中H和D的含量。根据反应前气相中H和D的含量，由质量守恒定律求得固相中H和D的含量。根据气、固两相中的氕氘原子数之比（D／H），由公式α（H-D]=（ED3／[H]）（目目）／（ED3／[H]）（气相）计算得到H-D分离因子α（H-D）。结果表明：20℃下，x0．03～1．00时，α（H-D）〉1．00，合金氢化物表现为正同位素效应。随着Mo含量的增加，α（H—D）由1．04增加到1．27；x〉0．50时，α（H-D）基本保持不变。2／7—0．03时α（H-D）≈1．00，合金表现为零同位素效应。根据以前热分析实验结果，TiMo0.03吸氢后析出大量负同位素效应的TiH2，并有少量正同位素效应的Ti—Mo合金氢化物，零同位素效应是两者共同作用的结果。根据Mo含量和分离因子的关系，室温下H原子倾向于占据4Ti四面体间隙位置，而D原子倾向于占据能量较高的3TilMo四面体间隙位置。

Effect of Mo Content on the Hydrogen Isotope Effect of Ti-Mo Alloy Hydrides

The alloys with various Mo content TiMox（x=0.03, 0.13, 0.25, 0.50, 1.00, Mo/Ti）were prepared with electromagnetic levitation technique. The alloys after activation react rapidly with H-D gas mixture (D%=50%), the composition of the mixture in equilibrium of isotope exchange was determined using a mass-spectroscopy. H-D separation factor α (H-D) is defined as (D/H)s/(D/H)g, in which (D/H)s refers to the ratio of D and H content in solid phase, and (D/H)g refers to the ratio of D and H content in gas phase. The results show that at 20℃, x = 0.03 ～ 1.00,α (H-D) >1.00, D prefers to stay at solid phase, and the preference becomes stronger as the Mo content increases, with α (H-D) rising from 1.04 to 1.27. α (H-D) keeps nearly unvaried when x=0.50～1.00. α (H-D) ≈1.00 when x=0.03, namely TiMo0.03 hydride shows zero effect, through previous TG-DSC analysis results, the hydride contains TiH2 with negative effect, and Ti-Mo hydrides with positive effect, so it is the total effect of the two hydrides with opposite effect. From the relationship between the Mo content andα (H-D) H atom prefers to take 4Ti tetrahedral interstice, whereas D atom tends to take 3Ti1Mo position in which the energy level is higher than that of 4Ti position.