Atomic ordering and systematics of bonding lengths in the Ti–V omega phase: a neutron diffraction study

BENITES, G.M.; AURELIO, G.; A. FERNÁNDEZ GUILLERMET; CUELLO, G. J.; BERMEJO, F.J.

JOURNAL OF ALLOYS AND COMPOUNDS

Elsevier

Lugar: Amsterdam; Año: 1999 vol. 284 p. 251 - 255

0925-8388

A new model describing the structural and bonding properties of the omega (V) phase in Zr–Nb alloys has recently been presented [12]. This model, which was aimed at explaining the composition dependence of the bonding lengths, predicts that the V phase is ordered,i.e., that some crystallographic sites are preferentially occupied by Zr atoms. Such feature, which should in principle be observed in other related V phases, has not yet been tested against direct measurements. This problem has now been studied in the Ti–V system, which is the analogue of Zr–Nb in the 3d-transition series. Neutron diffraction measurements have been performed in quenched Ti–Valloys withV contents between 14 and 17 at.%. The diffraction spectra have been analysed using the Rietveld method, and a systematic analysis is reported here of the possibility of deviations from the random occupation of the two sublattices which are distinguished in the V structure. In addition, these new diffraction data are used in an evaluation of the shortest interatomic distances which are relevant for a comparison with the predictions of the model of Grad et al.