Effect of solutes in binary columbium (Nb) alloys on creep strength

Klein, Mark J.; Metcalfe, A. G.

doi:10.1007/bf02669388

Cited by 12 publications

(4 citation statements)

References 2 publications

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“…Single crystal investigations below 400 K indicated that Nb is significantly strengthened by Mo, while not by Ta [2]. Similar results have been obtained in polycrystals even at high temperatures [3][4][5][6][7][8][9]. Generally, solid-solution strengthening in Nb is closely related to the size misfit of the solute [3]; that is, the solute having a large size misfit to Nb such as Mo, exerts significant influence on the solid-solution strengthening.…”

Section: Introductionsupporting

confidence: 68%

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Solid-Solution Strengthening by Oxygen in Nb-Ta and Nb-Mo Single Crystals

Miura

Yoshimi

Hanada

2001

phys. stat. sol. (a)

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We have investigated the high-temperature solid-solution strengthening by oxygen in Nb, Nb-Ta and Nb-Mo single crystals by compression tests with constant strain rate. Nb, Nb-20Ta, Nb-40Ta, Nb-20Mo, and Nb-40Mo single crystals with various O content were grown by use of the electron-beam floating zone melting method. It is found that Nb and Nb-Ta single crystals are strengthened by oxygen at temperatures below 1100 K, while Nb-20Mo single crystals are strengthened even at 1473 K. The critical resolved shear stress (c.r.s.s.) of Nb-Ta single crystals at 298 K increases linearly with increasing O content, irrespective of Ta content. Furthermore, the increment of c.r.s.s. of Nb-Ta single crystals is larger than that of Nb. The c.r.s.s. of Nb-Mo single crystals is higher than that of Nb for all temperatures tested, and the c.r.s.s. of Nb-20Mo single crystals also increases with increasing O content. These results indicate that the interstitial-substitutional (i-s) interaction between O and Ta or Mo affects the mechanical properties in the Nb-based alloys at high temperature.

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Section: Introductionsupporting

confidence: 68%

“…There have been several reports on solid-solution strengthening of Nb by substitutional elements (see, e.g. [2][3][4][5][6][7][8][9]). Single crystal investigations below 400 K indicated that Nb is significantly strengthened by Mo, while not by Ta [2].…”

Section: Introductionmentioning

confidence: 99%

Solid-Solution Strengthening by Oxygen in Nb-Ta and Nb-Mo Single Crystals

Miura

Yoshimi

Hanada

2001

phys. stat. sol. (a)

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“…[12,15] It is well known that the solid solution strengthening cannot be interpreted solely on the basis of atomic size misfit, but reflects a combination of atomic size and other effects, such as an elastic modulus misfit or solute association effects. [4] Recently, Hideaki et al [16] realized the mechanism of the low elastic modulus of the Ti binary alloys, i.e., the valence electron number per atom (EPA) of Ti binary alloy can be controlled by the quantity of VB or VIB family element, resulting in a low Young's modulus material. At the same time, the effect of alloying on the phase stability of group VB (V, Nb, and Ta) transition metals has been studied by Landa et al [17] and two dominant mechanisms are recognized.…”

Section: Introductionmentioning

confidence: 99%

Elastic properties of Nb-based alloys by using the density functional theory

Liu¹,

Shang²

2012

Chinese Phys. B

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A first-principles density functional approach is used to study the electronic and the elastic properties of Nb15 X (X = Ti, Zr, Hf, V, Ta, Cr, Mo, and W) alloys. The elastic constants c11 and c12, the shear modulus C′, and the elastic modulus E〈100〉 are found to exhibit similar tendencies, each as a function of valence electron number per atom (EPA), while c44 seems unclear. Both c11 and c12 of Nb15X alloys increase monotonically with the increase of EPA. The C′ and E〈100〉 also show similar tendencies. The elastic constants (except c44) increase slightly when alloying with neighbours of a higher d-transition series. Our results are supported by the bonding density distribution. When solute atoms change from Ti(Zr, Hf) to V(Ta) then to Cr(Mo, W), the bonding electron density between the central solute atom and its first neighbouring Nb atoms is increased and becomes more anisotropic, which indicates the strong interaction and thus enhances the elastic properties of Nb—Cr(Mo, W) alloys. Under uniaxial 〈100〉 tensile loading, alloyed elements with less (more) valence electrons decrease (increase) the ideal tensile strength.

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“…However, because of the great affinity of Nb and Nb-base alloys for interstitial elements such as H, N, O, and C, the alloys react readily with the reactive gases containing the interstitials, causing striking changes in their physical and mechanical properties. [1][2][3][4][5][6][7][8][9] For example, 1 at. pct nitrogen (Ϸ0.15 wt pct) dissolved in niobium increases its hardness by about 270 pct and its electrical resistivity by about 30 pct.…”

Section: Introductionmentioning

confidence: 99%

Absorption kinetics and mechanisms of carbon monoxide in liquid niobium

Park

Abbaschian

1997

Metall Mater Trans B

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Absorption kinetics and mechanisms of carbon monoxide in liquid niobium were investigated in the temperature range of 2700 to 3000 K in samples levitated in a CO/Ar stream. The carbon and oxygen dissolution in liquid niobium from CO gas is an exothermic process, and the solubilities of carbon and oxygen (Ce, Oe in at. pct) are related to temperature (T in kelvin) and partial pressure of CO (P co in atm) as follows:ln Ce ϩ ln Oe Ϫ P co ϭ 2.32 ⅐ 10 4 /T Ϫ 2.35The reaction CO → [C] ϩ [O], which occurs along with the evaporation of niobium oxide during the absorption of carbon and oxygen, is a second-order process with a first-order dependence on C and O concentrations, respectively. The absorption mechanism implies that the overall reaction rate is controlled by the substep of dissociation of surface-adsorbed CO molecules. The rate equations for C and O absorption are given as follows:where C and O are carbon and oxygen concentrations in atomic percent, respectively, A is the surface area of the sample in cm 2 , and V is the volume in cm 3 .

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Effect of solutes in binary columbium (Nb) alloys on creep strength

Cited by 12 publications

References 2 publications

Solid-Solution Strengthening by Oxygen in Nb-Ta and Nb-Mo Single Crystals

Solid-Solution Strengthening by Oxygen in Nb-Ta and Nb-Mo Single Crystals

Elastic properties of Nb-based alloys by using the density functional theory

Absorption kinetics and mechanisms of carbon monoxide in liquid niobium

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