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 TiFe 0.85-x Cr 0.15 Zr x (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, MgZn 2 -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 (MgZn 2 -type phase). The decrease of the reversible hydrogen storage capacity is due to the formation of the stable hydrides Cr 2 ZrH 3 and TiH 2 , which start to decompose at around 700 °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. • TiFe 0.85- x Cr 0.15 Zr x (x = 0, 0.05, 0.10 and 0.15) alloys were prepared. • Regulating Zr content changed effectively the first hydrogenation properties. • MgZn 2 -type phase could act as a pathway to assist hydrogen diffusion. • Oxidation resistance increased with the introduction of Zr content. • Two kinds of irreversible hydrides were formed in the hydrogenation process of the alloys with Zr. [ABSTRACT FROM AUTHOR]