Atomic ordering and systematics of bonding lengths in the Ti–V omega phase: a neutron diffraction study
- 作者：Benites ; G.M. ; Aurelio ; G. ; Guillermet ; A. Ferná ; ndez ; Cuello ; G.J. ; Bermejo ; F.J.
- 关键词：Ti alloys ; Omega-phase ; Crystal structure ; Bonding ; Phase stability
- 刊名：Journal of Alloys and Compounds
- 出版年：1999
- 期刊代码：45_09258388
- 类别：ms
- 出版时间：March 4, 1999
- 卷：284
- 期：1-2
- 页码：251-255
- 文件大小：245 K
摘要
A new model describing the structural and bonding properties of the omega (Ω) 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 Ω 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 Ω 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–V alloys with V 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 Ω 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.