ZIRCONIUM IRON DISPROPORTIONATION DURING HYDRIDING REACTIONS IN NUCLEAR GETTERING OPERATIONS

We have investigated the hydriding properties of Zr2Fe and Zr3Fe alloys, including SAES Getters St-198. It was found from examining the X-ray diffraction patterns of alloys hydrided at temperatures ranging from 303 K to 773 K that disproportionation occurs in the Zr2Fe alloys at temperatures above 673 K. In Zr3Fe the temperature at which disproportionation takes place is much lower being between 473 and 573 K. In order to study the thermodynamics of hydride formation for these alloys pressure composition isotherms were recorded at temperatures between 303 and 773 K. Similarities in the x-ray diffraction patterns of partially hydrided Zr2Fe and Zr3Fe samples has prompted the use of inelastic neutron scattering to characterize the hydride products formed. I