| Nb-Ti-Ni ternary alloys have been selected to investigate the effect of composition on their hydrogen permeation properties in the work. Devanathan-Stachurski of electrolytic cell permeation experiments were employed to determine the hydrogen diffusion coefficient (D) of these alloy based membranes, which describes hydrogen diffusion behavior directly. The relationship between phases structure and D was investgated via X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA) and energy disperse spectroscopy (EDS). Also, the resistance of the membrane to hydrogen embrittlement occurred after electrochemical hydrogen diffusion experiment, were also analized. The magnetic-field-heat-treatment (MFHT) method was used for sample preparation, and the effect of MFHT on microstructure, hydrogen permeation properties of these samples and mechanical properties of alloys were also discussed.Electroless Pd plating are affected by plating parameters, like time, temperature, PH value, sensitization and activation process, composition of bath etc. An optical plating parameters are founded out as, T=70℃, Time=2h, C(NH4OH)=4.5mol/L, pH=9.8. The results revealed that prepared Pd coat appeared to be a particle-deposited surface image with amorphous microstructure, consisting of numerous spherical particles (1μm or so) arranged in single-layer form, the content of P in the coats is about 3%～4%. Such coat can keep its original appearance, but slight increase of particle size, strong intensity of Pd phase and Pd6P have been observed after heat treatment at 675K. The sequent hydrogen permeationg tests approve that the amorphous Pd membrane can improve the hydrogen diffusion capacity of alloy membranes significantly.Hydrogen diffusion coefficient (D) were determined by electrochemical experiments with dual-Devanathan-Stachurski electrolytic cell. The effect of phase ratio and phase structure on D were analyzed. The result presents that Nb-Ti-Ni alloys with two-phase structure have high D value. D increses with the increase of Nb; but decreases with the increase of Ni, Ti element. The phase ratio, the grain morphology and the arrangement of the alloy grains are changed after processing the alloy membranes with magnetic filed along different direction (parallel membrane surface, cross membrane surface and a 45°rational-rotation of membranes), which improved hydrogen diffusion coefficient effectively. The improvment of performance for hydrogen permeability alloys were vary with different directions of the magnetic field on the hydrogen separation membranes, and parallel direction of the magnetic field treatment on the alloys increases D the most remarkable.Mechanical properties of Nb-Ti-Ni alloy membranes were evaluated by 3-point bending test, which describes resistance to the hydrogen embrittlement of alloy membranes. The results show more heavy hydrogen embrittlement with the increace of Nb contant; while, the increace of Ni, Ti will improve the resistance to hydrogen embrittlement of Nb-Ti-Ni alloys membrane. The results of MHFT indicate that extra MHFT with different directions (parallel membrane surface, cross membrane surface and a 45°rational-rotation of membranes) can refuse grain size, change solid solution phase ratio, as well as benefit the formation of grains arrangment direction, which improved anti-hydrogen embrittlement of alloys. Especially,the case treated by MFHT of 45°rational-rotation improved the ability to resistance to hydrogen embrittlement significantly.Elastic recovery mechanism of hydrogen separation membrane were analysed with the Wide Hysteresis Shape Memory Effect of Nb-Ti-Ni Alloy form lattice structure. The theory explained the mechanical model of Nb-Ti-Ni alloy in the process of hydrogen permeation. The stress generated in solid solution of alloys by hydrogen absorption is mitigated and limited due to a wide hysteresis shape memory effect, confirming the good diffusion model of Nb-Ti-Ni hydrogen diffusion alloy membrane, which provides a rich theoretical interpretation and application model for design and performance improvement of hydrogen permeation alloy membranes.
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