Self-diffusion of Ti, Zr, and Hf in their hcp phases, and diffusion of Nb95 in hcp Zr

Dyment, F.; Libanati, César M.

doi:10.1007/bf00550978

Cited by 186 publications

(27 citation statements)

References 14 publications

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“…The material purity with respect to Fig. 1-Arrhenius diagrams for self-diffusion in nominally pure ␣ -Zr [1][2][3]7] the fast-diffusing metallic solutes, such as Fe or Ni, plays and ␣ -Ti. [5,6] an especially important role.…”

Section: A Materialsmentioning

confidence: 99%

“…This property is likely revealed "abnormal" behavior with a pronounced curvature to be responsible for the interstitial dissolution of small of the Arrhenius plot (Zr [1,2,3] ) or an unusually small activametallic elements (such as Fe, Ni, and Co), which diffuse tion enthalpy (Ti [4,5,6] ) ( Figure 1). These diffusion data devieven faster than small nonmetallic atoms, such as C or O ate from the common empirical rules derived for closed- (Figure 2).…”

Section: Introductionmentioning

confidence: 97%

“…hcp metals. Materials used in the first experiments [1,2,5,6] had Generally, the vacancy concentration, c v , in the presence of a 99.9 wt pct purity, and only recently high-purity Ti [10] and strongly interacting impurities, is increased by the amount Fe-free Zr [11] became available to diffusion investigations.…”

Section: Introductionmentioning

confidence: 99%

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Bulk and interface boundary diffusion in group IV hexagonal close-packed metals and alloys

Herzig

Divinski

2002

Metall and Mat Trans A

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Bulk and grain boundary (GB) self-diffusion and substitutional solute diffusion in group IV hexagonal close-packed (hcp) metals (␣ -Ti, ␣ -Zr, and ␣ -Hf) are reviewed. The recent results obtained on high-purity materials are shown to approach closely the "intrinsic" diffusion characteristics. The enhancement effect of fast-diffusing impurities (such as Fe, Ni, or Co) is discussed for both self-and substitutional bulk solute diffusion in terms of the interstitial solubility of the impurity atoms. In GB self-diffusion, the impurity effect is found to be less dramatic. The results obtained on high-purity hcp materials can be interpreted in terms of intrinsically 'normal' vacancy-mediated GB diffusion, with the ratio of GB to volume diffusion activation enthalpies of Q gb /Q Ϸ 0.6. The GB self-diffusion in group IV hcp metals reveals distinct systematics. Bulk self-diffusion and fast interstitial solute diffusion (Fe and Ni) in the hcp phase ␣ 2 -Ti 3 Al are reviewed. Interphase boundary diffusion of Ti in the unidirectional lamellar ␣ 2 /␥ structure of the two-phase Ti 48 Al 52 alloy is analyzed with respect to the phase boundary structure and GB self-diffusion in ␣ 2 -Ti 3 Al.

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Section: A Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Bulk and interface boundary diffusion in group IV hexagonal close-packed metals and alloys

Herzig

Divinski

2002

Metall and Mat Trans A

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“…No physical model has been given by the authors to explain this anomaly. Hood [10] has suggested that such anomaly might be produced by the more rapid diffusion of impurities present in e-Zr but, to date, no clear explanation has been given for this behaviour.It is the purpose of this letter to introduce new elements into the discussion of the self-diffusion coefficient of e-Zr, including new values obtained from an analysis of results obtained by mechanical testing, in the temperature region 633 to 695 K.The results found by Horv~ith et al [9] indicate that Dv is, approximately, two orders of magnitude lower than the value reported by Dyment and Libanati [7], which was attributed to a higher dislocation density, causing a higher diffusion rate through the dislocations core. This interpretation agrees with the theoretical work of Hart …”

mentioning

confidence: 78%

“…In fact, the first results were published by research groups of the Soviet Union [1][2][3][4] and Argentina [7] and, in both cases, the measurements were performed at temperatures near the ~ to/~ phase transition and in polycrystals.Hood and Schultz [8] measured Dv in e-Zr single crystals at 1124 K, oriented for diffusion parallel and perpendicular to the hexagonal axis. The most recent and important work in this field, however, was presented by Horvfith et al [9] where the self-diffusion coefficient was measured between 779 and 1128K, using ion-beam-sputtering techniques.…”

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confidence: 94%

Self-diffusion coefficient ofα-zirconium

1987

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In recent years several investigators have studied the self-diffusion coefficient of zirconium, Dv, both in the alpha phase of the pure metal and in dilute zirconium alloys [1][2][3][4][5][6][7][8][9]. In fact, the first results were published by research groups of the Soviet Union [1][2][3][4] and Argentina [7] and, in both cases, the measurements were performed at temperatures near the ~ to/~ phase transition and in polycrystals.Hood and Schultz [8] measured Dv in e-Zr single crystals at 1124 K, oriented for diffusion parallel and perpendicular to the hexagonal axis. The most recent and important work in this field, however, was presented by Horvfith et al. [9] where the self-diffusion coefficient was measured between 779 and 1128K, using ion-beam-sputtering techniques. The authors found an anomalous behaviour in the metal, because Dv does not follow an Arrhenius law. No physical model has been given by the authors to explain this anomaly. Hood [10] has suggested that such anomaly might be produced by the more rapid diffusion of impurities present in e-Zr but, to date, no clear explanation has been given for this behaviour.It is the purpose of this letter to introduce new elements into the discussion of the self-diffusion coefficient of e-Zr, including new values obtained from an analysis of results obtained by mechanical testing, in the temperature region 633 to 695 K.The results found by Horv~ith et al. [9] indicate that Dv is, approximately, two orders of magnitude lower than the value reported by Dyment and Libanati [7], which was attributed to a higher dislocation density, causing a higher diffusion rate through the dislocations core. This interpretation agrees with the theoretical work of Hart It is interesting to point out that the anomalous variation of Dv with the temperature can be accounted for by considering an analogous electrical model of fluxes in series [15], where

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Characterization of Hot Workability for a Near Alpha Titanium Alloy by Integrating Processing Maps and Constitutive Relationship

Zhou

Zeng

et al. 2019

Adv Eng Mater

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Hot workability of near‐alpha titanium alloy Ti–6Al–3Nb–2Zr–1Mo with an initial duplex microstructure is evaluated through isothermal compressions in lower α + β phase field, upper α + β phase field, and β phase field. It is noteworthy that flow stress increases with increasing strain rates and decreasing temperatures. Based on Dynamic Material Model and Prasad's instability criterion, processing maps are established and subdivided into six characterization regions to ascertain deformation mechanisms connected with microstructure. The results show that super‐plasticity deformation (SPD) and dynamic recrystallization (DRX) of β phase can be achieved in the area with high power dissipation efficiency in α + β phase field and β phase field, thus making them being the optimum hot working domains. Besides, DRX of lamellar α, dynamic recovery (DRV) of equiaxed primary α (αp) as well as DRV of β phase occur in the remaining safe domains with increasing temperature. The microstructure in instability domains, where hot deformation should be kept away, is characterized by flow localization. Arrhenius‐type constitutive model incorporated with strain compensations is selected to describe the high‐temperature flow behavior of the test Ti‐alloy. The introduction of three detailed divisions with temperature ranges gives an accurate calculation for apparent activation energy.

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Self-diffusion of Ti, Zr, and Hf in their hcp phases, and diffusion of Nb95 in hcp Zr

Cited by 186 publications

References 14 publications

Bulk and interface boundary diffusion in group IV hexagonal close-packed metals and alloys

Bulk and interface boundary diffusion in group IV hexagonal close-packed metals and alloys

Self-diffusion coefficient ofα-zirconium

Characterization of Hot Workability for a Near Alpha Titanium Alloy by Integrating Processing Maps and Constitutive Relationship

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