ELECTRONIC-STRUCTURE CHANGES ASSOCIATED WITH A MARTENSITIC-TRANSFORMATION IN A TI50NI48FE2 ALLOY STUDIED BY ELECTRON-ENERGY-LOSS SPECTROSCOPY

Changes in the 3d occupancy associated with a martensitic transformati on in a Ti50Ni48Fe2 alloy was investigated by electron energy-loss spe ctroscopy (EELS). The white-line intensity of both Ti- and Ni-L-2,L-3, edges,which reflects the unoccupied density-of-states in 3d band, was compared before and after the martensitic transformation, where the i ntensity change was observed by both the peak intensity and the integr ated intensity measurements. It was found that the white-line intensit y of Ti-L-2,L-3 edges in the parent phase (cubic) was slightly larger than that in the martensite (monoclinic), whereas the intensity of Ni- L-2,L-3, edges in the parent phase was slightly smaller than that in t he martensite. The result indicates that the unoccupied density-of-sta tes in Ti-3d band tend to be reduced with the cubic to monoclinic mart ensitic transformation, while those in Ni-3d band to be increased. The present investigation, where core-loss measurements of EELS were appl ied for a martensitic transformation for the first time, convinced tha t EELS is sensitive to observe small electronic structure changes with this type of transformation.