Nb-Ti-Ni体系合金的结构及其氢渗透性能

Phase structure and hydrogen diffusion properties of Nb-Ti-Ni alloys

以Ni30Ti31Nb39为成分基点,通过合金成分的规律性调整(5%,原子数分数),研究系列Nb-Ti-Ni体系合金的相结构与氢渗透性能。研究结果表明:制备的Nb-Ti-Ni合金有两相和三相共2种相结构;两相合金由bcc-Nb(Ni,Ti)固溶体和(bcc-Nb(Ni,Ti)+β2-NiTi)共晶相构成;三相合金除上述两相外,还有少量NiTi2相;两相结构合金的氢渗透性能优于三相结构合金性能,合金中Nb含量越多,bcc-Nb(Ni,Ti)固溶体相含量越大,合金的氢扩散系数(D)增大;Ni和Ti含量增大,则降低了固溶体相的比例,不利于合金氢扩散性能提高;Nb-Ti-Ni体系合金的氢扩散系数为10-9数量级,Nb49Ni25Ti26合金的氢扩散系数最大(5.260 5×10-9 m2/s)。

Effect of composition,phase ratio of Nb-Ni-Ti alloys on its hydrogen diffusion properties was investigated,where the composition of Ni30Ti31Nb39 was the original one,the alloy composition was adjusted at 5%（mole fraction）.Hydrogen diffusion coefficient（D） was measured in Devanathan-Stachurski（D-S） dual-cell system.The results indicate that these alloys are two-phase structure,or three-phase structure,consisting of the primary bcc-Nb（Ni,Ti） solid solution phase,（bcc-Nb（Ni,Ti）＋β2-NiTi） eutectic phase,and a small amount of NiTi2 phase（observed in three-phase alloy）.Two-phase alloys show better hydrogen diffusion properties than three-phase alloys,the increase of Nb content will lead to a higher percent of bcc-Nb（Ni,Ti） solid solution phase,and then a higher value of D increase;while the increase of Ni and Ti content will result in a lower value of D due to the decrease of the percentage of solid solution.Hydrogen diffusion coefficient（D） of these samples reaches the magnitude of 10-9 m2/s,the max value（5.2605×10-9 m2/s） is observed in the case of Nb49Ni25Ti26 alloy.