Analysis of FeTi hydride alloys by thermal analysis, small angle neutron scattering and positron annihilation

Samples of vapour deposited FeTi and electrochemically loaded with hydrogen from LiOH solution have been examined by thermal analysis, positron annihilation and small angle neutron scattering techniques. Thermal analysis shows that the FeTi loads hydrogen without the need for activation although there was not a good correlation between the amount of hydrogen loaded and duration of loading. Positron annihilation and SANS on the untreated sample showed that the alloy was highly disordered in nature and contained a large concentration of vacancy clusters. SANS also showed an increase in the interfacial scattering surface area following hydrogen loading, consistent with an increase in voidage within the structure. Positron annihilation on the other hand suggested a decrease in the concentration of vacancies following hydrogen loading. It was concluded that some of the voids within the structure were filled by hydrogen gas which caused a decrease in the positron lifetime. However, not all of the voids were filled with gas.