Electrode characteristics of nanostructured TiFe and ZrCr2 type metal hydride prepared by mechanical alloying

Mechanical alloying (MA)process has been introduced to produce nanocrystalline AB (TiFe) and AB(2) (ZrCr2) type metal hydride. MA process has recently emerged as a novel technique for producing alloy powders whose structures are nanocrystalline and/or amorphous. Ti-Fe and Zr-Cr systems were prepared using the planetary ball mill, starting from both elemental ponders and from pre-melted intermetallics. The structure of the powder after milling has been examined by XRD, TEM and HREM. Hydrogenation properties and electrochemical measurements have been investigated. Both Ti-Fe and Zr-Cr system showed a nanocrystalline structure after ball milling of both pre-melted alloy and elemental powders. The plateau pressure for hydrogenation of nanocrystalline alloy was lower than that of its conventional polycrystalline counterpart. MA Ti-Fe alloys had a higher discharge capacity than the arc-melted one. However, the discharge capacity of MA ZrCrNi alloy was lower than that of the are-melted one. (C) 1998 Acta Metallurgica Inc.