PSI - Issue 40

E.D. Kurbanova et al. / Procedia Structural Integrity 40 (2022) 251–257 Kurbanova E.D., Polukhin V.A./ / Structural Integrity Procedia 00 (2022) 000 – 000

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3. Hydrogen embrittlement It is well established that the interaction of hydrogen with metals leads to a deterioration in their mechanical properties due to the formation of hydrides and the subsequent development of hydrogen brittleness of membrane alloys Song et al. (2011), Dolan et al. (2013) However, elements of group 5 in their pure form lose their plasticity due to embrittlement at increased hydrogen concentrations near H / M = 0.25 not only at low temperatures, but also at functional temperatures in the range 573-773 K. However, with all advantages of these metals, the problem of hydrogen embrittlement is solved by creating not only binary alloys, but also ternary ones with alloying with elements Ti, Zr, and W. This is achieved by appropriate selection of their concentrations ensuring resistance to hydrogen embrittlement Polukhin et al. (2017), Yukawa et al. (2011). Fig. 4 shows for comparison the curves for the membrane alloy Ta 94.9 W 5.1 and for pure Ta Polukhin et al. (2018), Veleckis et al. (1969), which characterize the processes of hydrogenation and permeability. The contrast in the efficiency of the alloyed W alloy is obvious precisely due to the inhibiting properties of W and the effect of blocking hydride formation.

Fig. 4. Curves for the Ta 94.9 W 5.1 alloy obtained for the temperature range 673-773 K and hydrogen concentrations up to 0.6 H/M Yukawa et al. (2011). For comparison, the curve for pure at 673 K is also shown Kozhakhmetov et al. (2015).

The presence in the alloy lowers the accumulative absorption of hydrogen, its concentration and to a greater extent prevents the formation of hydrides and blocks the development of hydrogen embrittlement in this alloy in comparison with the alloy Kozhakhmetov et al. (2015). However, the efficiency of vanadium alloys also decreases due to hydrogen β -embrittlement, which is effectively the introduction of the alloying Ti and Ni. The effect of which is manifested by a decrease in the intensity of hydrogen absorption and the subsequent phase transition, classified as α -hydrogenation. Nevertheless, Ti-V-Ni alloys are still feasible for membrane technology for producing high-purity hydrogen. All these effects in the considered membrane alloys were revealed by tracking hydrogen permeability and the specificity of diffusion transport, the concentration of dissolved hydrogen using an original setup (IMET RAS) Polukhin et al. (2019). The X-ray structural transformations have been recorded: the identificated of compounds (NiTi, NiTi 2 ) and hydrides with revealed quantitative volume of membranes, including thermal effects, which also were determined the thermal stability of membranes and their functionality specified with the temperature and pressure. 4. Conclusion It is shown that the alloying of metals Ni, Nb and V leads to the formation of highly supersaturated solid solutions Nb 85 Ni 15 and V 85 Ni 15 in the form of dendritic solid solutions by nickel segregation, strengthening membrane alloys. With the partial (5%) replacement of Ni atoms by those of titanium in the ternary alloy, microscopic interdendride phases NiTi and NiTi 2 are formed along with their main solid solution, the membrane