Tailoring hydrogenation and anti-oxidation properties of titanium - iron - chromium alloys by regulating zirconium content at room temperature

The effects of Fe substitution by Zr on the microstructure, hydrogen storage properties and oxidation resistance of the TiFe0.85-xCr0.15Zrx (x = 0, 0.05, 0.10, 0.15) alloys are studied in this work. It is shown that all the alloys are consisted of TiFe phase, MgZn2-type phase and minor Ti phase. The introduction of Zr causes no change for the TiFe main phase. All the alloys absorb hydrogen directly under mild conditions without any activation process. As Zr content increases, the maximum hydrogen storage capacity of the first hydrogenation increases while the reversible hydrogen storage capacity decreases. The marked change of the first hydrogenation properties may be due to the formation of the bright phase (MgZn2-type phase). The decrease of the reversible hydrogen storage capacity is due to the formation of the stable hydrides Cr2ZrH3 and TiH2, which start to decompose at around 700 degrees C. During the air exposure test, the alloys with higher Zr content show good oxidation resistance. For the PCT measurement, the alloys with higher Zr show lower hydrogen absorption and desorption platform pressure, which means more stable hydrides are formed during the first hydrogenation. Moreover, the rate limiting step model of the first and fifth hydrogenation processes of all the alloys has also been investigated in detail.

Automated summary

This study investigates the effects of Fe substitution by Zr on the microstructure, hydrogen storage properties, and oxidation resistance of TiFe0.85-xCr0.15Zrx (x = 0, 0.05, 0.10, 0.15) alloys. The results show that the introduction of Zr does not change the main phase of TiFe, but it affects the hydrogen storage capacity and oxidation resistance. With increasing Zr content, the first hydrogenation capacity increases while the reversible hydrogen storage capacity decreases. The alloys with higher Zr content exhibit good oxidation resistance and form more stable hydrides during the first hydrogenation.