Systematics of lattice parameters and bonding distances of the omega phase in ZrNb alloys

Grad, Gabriela B.; Pieres, J. J.; Guillermet, A. Fernández; Cuello, G.J.; Granada, J.R.; Mayer, R.E.

doi:10.1016/0921-4526(95)00180-h

Cited by 31 publications

(34 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…revealed remarkable regularities in the composition dependence of the IDs in the ⍀ phase, [3][4][5][6] which motivated a THE relation between structure, phase stability, and systematic study of the properties of this phase and its relachemical bonding is a key ingredient of the physico-chemical tions to other metastable structures in alloys formed by the approach to material systems. For stable phases, it is often elements of the Ti-group (Ti, Zr, Hf) with other TMs.…”

Section: Introductionmentioning

confidence: 99%

Metastable phases in the Ti-V system: Part I. Neutron diffraction study and assessment of structural properties

Aurelio

Guillermet

Cuello

et al. 2002

Metall Mater Trans A

Self Cite

View full text Add to dashboard Cite

This article presents the results of a neutron diffraction study of a series of quenched Ti-V alloys and an assessment of the composition dependence of the structural properties in the Ti-V system. Upon quenching to room temperature and atmospheric pressure, three metastable phases occur, viz., the hcp (␣ Ј) phase formed by a martensitic transformation, the omega (⍀) phase formed by a displacive transformation involving the collapse of the (111) planes of the bcc structure, and the untransformed bcc (␤ ) phase. The lattice parameters (LPs) of the ␣ Ј, ␤, and ⍀ phases are determined as functions of the V content in the composition range 3 Յ at. pct V Յ 70. This information is combined with a detailed analysis of the available experimental data on the ␣ Ј, ␤, and ⍀ phases in pure Ti and Ti-V alloys and the ␤ phase of V. New estimates for the LPs of ␤ and ⍀ Ti and expressions describing the composition dependence of the LPs are presented. Using the assessed values, various open questions are discussed, i.e., the composition range where the hexagonal to trigonal symmetry change is observed in the ⍀ phase, the applicability of an approximation involved in the plane collapse model for the ␤ → ⍀ transformation, and the extent to which the so-called Jamieson correlation for interatomic distances in the ⍀ phase holds for Ti.

show abstract

Section: Introductionmentioning

confidence: 99%

Metastable phases in the Ti-V system: Part I. Neutron diffraction study and assessment of structural properties

Aurelio

Guillermet

Cuello

et al. 2002

Metall Mater Trans A

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, by quenching hightemperature bcc alloys to room temperature, it is possible to obtain retained metastable bcc phases. Grad et al (1995) performed neutron scattering study of the quenched Zr-Nb bcc alloys and found a linear relation between the lattice parameter and the alloy composition at room temperature. Combining with previous data, they extrapolated to pure bcc Zr and obtained a value of the lattice parameter at room temperature.…”

Section: Bcc Ti and Bcc Zrmentioning

confidence: 99%

Theoretical modeling of molar volume and thermal expansion

2005

View full text Add to dashboard Cite

“…The zero-pressure volume determined for the b phase from EOS is 22.06 Å 3 /atom, which is line with the 22.19 Å 3 /atom determined from the neutron diffraction measurements conducted on various compositions of the Zr-Nb alloy. [28] Figure 4 also shows that the energy of the b phase is always lower than that of the x phase under all the hydrostatic compressions, and the energy difference increases with increasing compression up to V/V 0 = 0.86 with a corresponding pressure of 17.5 GPa (the compression up to which calculations have been performed), suggesting no b fi x transformation under hydrostatic compression up to 17.5 GPa. Our experimental finding is in agreement with the theoretical calculations.…”

Section: Resultsmentioning

confidence: 86%

“…The d substates (d z 2 ,d x 2 Ày 2 , d xy , d yz and d xz ) in the hexagonal symmetry decompose into three irreducible representations, d z 2 , d x 2 Ày 2 þ d xy and d xz + d yz . [28] We observe that in the x stability region, the dominant contributions are from the d xz + d yz character at the Al site and d z 2 and d x 2 Ày 2 þ d xy character at the B site (in fact, at the B site the average charge per state of both the characters is almost equal). On increasing pressure (decreasing volume) the populations of all the partial d states increase, but the increase is largest for the d z 2 state.…”

Section: B Ti Zr and Hfmentioning

confidence: 95%

Experimental and Theoretical Investigations on d and f Electron Systems under High Pressure

Gupta

Joshi

Banerjee

2007

Metall Mater Trans A

View full text Add to dashboard Cite

The pressure-induced electron transfer from sp to d band in transition elements, and spd to f band in the light actinides significantly influences the stability of crystal structures in these metals. Although a fi x fi b phase transition with increasing pressure in group IV transition elements is well documented, the b fi x transition under pressure has not been reported until recently. Our experimental study on the b-stabilized Zr-20Nb alloy reveals that it transforms to x phase on shock compression, whereas this transition is not seen in a hydrostatic pressure condition. The platelike morphology of x formed under shock compression is in contrast to the fine particle morphology seen in this system under thermal treatment, which clearly indicates that the mechanism of the b fi x transformation under shock treatment involves a large shear component. In this article, we have analyzed why the x fi b transition pressures in Ti, Zr, and Hf do not follow the trend implied by the principle of corresponding states. Our analysis shows that the x fi b transition depends on how the increased d population caused by the sp fi d transfer of electron is distributed among various d substates. In Th, we have analyzed the role of 5f electrons in determining the mechanical stability of fcc and bct structures under hydrostatic compressions. Our analysis shows that the fcc to bct transition in this metal, which has been reported by high-pressure experiments, occurs because of softening of the tetragonal shear modulus C¢ = (C 11 -C 12 )/2 under compression. From the total energy calculated as a function of specific volume, we have determined the 0 K isotherm, which is then used to deduce the shock Hugoniot. The theoretical Hugoniot compares well with the experimental data.

show abstract

Systematics of lattice parameters and bonding distances of the omega phase in ZrNb alloys

Cited by 31 publications

References 9 publications

Metastable phases in the Ti-V system: Part I. Neutron diffraction study and assessment of structural properties

Metastable phases in the Ti-V system: Part I. Neutron diffraction study and assessment of structural properties

Theoretical modeling of molar volume and thermal expansion

Experimental and Theoretical Investigations on d and f Electron Systems under High Pressure

Contact Info

Product

Resources

About