Microstructural correlations with the hydrogenation kinetics of FeTi 1+ξ alloys

Abstract

The influence of β-Ti on the hydrogenation properties of FeTi 1+ξ alloys (0.1 ⩽ ξ⩽0.5) was investigated. The surface morphologies and chemical compositions before and after hydrogenation were examined. From the cracking features of the surfaces and X-ray diffraction analysis, it was concluded that the hydride of β-Ti was formed prior to hydrogenation of the FeTi matrix in these alloys. Formation of TiH 2 induced cracking into the FeTi matrix. Hydrogen was then transported through the cracks and absorbed by FeTi. Therefore, activation treatment was not required. In addition, the rate of hydrogen absorption of these alloys in the first few cycles was faster than that of FeTi 1.0. The difference in the kinetics of the first hydrogenation cycle of these alloys can be explained on the basis of the amount and distribution of the eutectic strips.