HYDROGEN ABSORPTION STUDIES IN ZR0.2TB0.8CO3 AND DECREPITATION AND CYCLIC STABILITIES IN ZR0.2TB0.8CO3 AND ZRMNFE

Pressure-composition isotherms have been determined for a Zr0.2Tb0.8Co 3 alloy in the ranges 10 less than or equal to P (mbar)less than or eq ual to 900 and 75 less than or equal to T (degrees C)less than or equa l to 200. The hydrogen absorption study shows that the substitution of Zr for Tb in TbCo3 results in the shift of the plateau region to high er equilibrium pressures with a reduction in the hydrogen capacity. An X-ray study on the hydrogenated Zr0.2Tb0.8Co3 alloy reveals that the alloy does not decompose upon hydrogenation. Particle size measurement s in Zr0.2Tb0.8Co3 and ZrMnFe alloys before and after hydrogenation sh ow that the decrepitation in Zr0.2Tb0.8Co3 is far less than that in th e much harder material ZrMnFe. A plateau pressure of near 1 bar at a t emperature suitable for practical applications can be conveniently obt ained by appropriate replacement of Tb by Zr in TbCo3. (C) 1997 Elsevi er Science S.A.