An experimental and theoretical study of the hydrogen resistance of Ti3SiC2 and Ti3AlC2

The hydrogen resistance of Ti3SiC2 and Ti3AlC2 is investigated by a combination of high temperature hydrogenation experiments and first-principles calculations. The hydrogen absorption rate in Ti3AlC2 powders is twice of that in Ti3SiC2. Hydrogenation leads to significant structure degradation on Ti3AlC2 by promoting the exudation of Al atoms which form Al bubbles on the powder surface, while the morphology of Ti3SiC2 is almost unchanged. The hydrogen-induced degradation on Ti3AlC2 is theoretically interpreted by the higher hydrogen diffusivity in Ti3AlC2 and the larger reduction of both formation energy and diffusion energy barrier of Al vacancy in Ti3AlC2 than that of Ti3SiC2.