The Microstructure Evolution And Hydrogen Permeability Performance Of The V-Ti-Co Ternary Alloy

Based on the concept of "share functions with the polyphase structures", V-Ti-Cohydrogen permeation materials is possible to designed by analyze the V-Ti-Co ternaryalloy in groups of means.In this article,36kinds of composition of V-Ti-Co ternary alloy is chosen to beanalyzed, using including scanning electron microscope (SEM), X-ray diffraction andother equipment to study as-cast organization and microstructure. The varying pattern ofmicrostructure morphology and phase composition of V-Ti-Co ternary alloy was studiedin different component. By the analysis of the as-cast microstructure, obtained theexpected composition range of higher hydrogen permeation effect of the ternary alloy.Ten different composition of V-Ti-Co ternary alloy is sellected and tested. By analyzingthe results of the hydrogen permeation test, the material hydrogen permeation mechanism,failure mechanism and hydrogen embrittleness of V-Ti-Co ternary alloy is studied.By analyze the difference of the microstructure and phase composition in differentcomposition of V-Ti-Co ternary alloy, found that with the increasing of the proportion ofingredients of V element and Ti element, the microstructure of V-Ti-Co ternary alloy ischanging from single-phase TiCo, to primary TiCo with eutectic [V(Ti)+TiCo], and thento pure eutectic [V(Ti)+TiCo], and then to V(Ti) solid solutions with eutectic[V(Ti)+TiCo], and at last to single-phase V(Ti) solid solutions. And found that when thecomposition of the pure eutectic V-Ti-Co ternary alloy is near the TiCo side, the eutectic[V(Ti)+TiCo] is becoming divorced eutectic.In the Hydrogen permeability tests of ten different points of composition, thepenetration experiment in six points have stable and effective results. Though theanalysis of the results, the conclusions is confirmed that the hydrogen flow rate (J×L) andthe difference between the square root of pressure(Pu0.5-Pd0.5) of the upstream anddownstream of the alloy diaphragm is linear related. The temperature rise will alsoimproved the hydrogen permeability of the V-Ti-Co ternary alloy. Noticed that V(Ti)express hydrogen permeation properties in the alloy. And confirmed the ideal hydrogenpermeation alloy is formed of primary V(Ti) solid solutions with eutectic [V(Ti)+TiCo].The study of hydrogen embrittleness is based on the analysis of hydrogenpermeation flow curve and the morphology after hydrogen embrittleness. The hydrogen embrittleness is found in four different compositions of V-Ti-Co ternary alloy. And foundthat hydrogen embrittleness mainly occurs in the V(Ti) solid solution phase. And whenthe composition of V-Ti-Co ternary alloy is in the divorced eutectic zone, with the largeblock of V(Ti) solid solution distributed asymmetrical in the alloy, the V(Ti) solidsolution phase is easy to crack under the action of hydrogen. Which means the hydrogenembrittleness mainly caused in V(Ti) solid solution. And the hydrogen embrittlenessfinally cause the failure of the V-Ti-Co ternary alloy.