EFFECT OF THE 2ND PHASE ON THE INITIATION OF HYDROGENATION OF TIFE1-XMX (M=CR, MN) ALLOYS

The hydrogen absorption characteristics of TiFe partially substituted with a small amount of Cr or Mn for Fe were studied. The morphology of the specimen surface was examined and the phases in the sample were identified. The microscopic composition differences for the individual phases were analyzed. It was observed that the samples required no activation for hydrogenation when a second phase was present. Increasing the amount of the second phase led to a higher activation rate, lower plateau pressure and higher maximum absorption capacity. Homogenization treatment at 900-degrees-C reduced the activation rate, but had no effect on the subsequent hydrogenation properties. The effects of substitution and homogenization on the hydrogenation of TiFe were correlated with the quantity and morphology of the second phase.