Effect of ball-milling with Ni and Raney Ni on surface structural characteristics of TiV2.1Ni0.3 alloy

Surface structural characteristics of TiV2.1Ni0.3-Ni and TiV2.1Ni0.3-Raney Ni composites, which were prepared by ball-milling a TiV2.1Ni0.3 alloy with Ni or Raney Ni under an Ar atmosphere, were investigated by X-ray diffractometry, Auger electron spectrometric analysis (AES) and so on. The ball-milling with Ni or Raney Ni did not influence the bulk crystal structure of the TiV2.1Ni0.3 alloy. The mutual diffusion layer, which was presumed to be responsible for retarding the progress of the corrosion, was found to be formed in the interface region between Ni and alloy components during the ball-milling with Ni or Raney Ni. The AES depth profile of the constituent elements for the TiV2.1Ni0.3-Ni composite, however, was different from the TiV2.1Ni0.3-Raney Ni composite due to the difference in the coverage and the homogeneity of the surface modification, which also influenced the time course of the rest potential. The ball-milling with Ni and Raney Ni greatly decreased the onset temperature of weight loss assigned to dehydriding from dihydride to monohydride and from monohydride to alloy. (C) 2001 Elsevier Science B.V. All rights reserved.