Literature Survey on Diffusivities of Oxygen, Aluminum, and Vanadium in Alpha Titanium, Beta Titanium, and in Rutile

Liu, Z.; Welsch, G.

doi:10.1007/bf02628396

Cited by 133 publications

(58 citation statements)

References 26 publications

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“…The commercially made sample (Figure 3(g)) has a subdiffusion of O in TiO 2 , the calculated [33] activation energy (251 kJ mol Ϫ1 ) is close to many of the experimental values stantially larger particle size than any of the premilled samples. This was not unexpected, as milling has been shown cited previously.…”

Section: Scanning Electron Microscopymentioning

confidence: 61%

Mechanical enhancement of the carbothermic formation of TiB2

Welham

2000

Metall Mater Trans A

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A mixture of rutile, boron oxide, and graphite has been mechanically milled for 1, 10, and 100 hours with the intention of forming titanium diboride during subsequent thermal treatment. The resultant powders were examined after isothermal annealing by X-ray diffraction (XRD) to determine the effect of milling on the formation of TiB 2 . No reaction was found to occur during milling, even for milling times of 100 hours. Annealing of the milled samples resulted in the formation of TiB 2 at temperatures as low as 1000 ЊC for the 100 c-hour milled powder. The reaction mechanism during thermal processing changed with milling time, with TiBO 3 predominant in samples milled for Ͼ1 hour, whereas Ti n O 2nϪ1 phases predominated for 1 hour of milling. Titanium carbide became an increasingly abundant intermediate phase with longer milling times, but was converted to TiB 2 at high temperatures. The annealed products showed the presence of acicular crystals of TiB2, with those from 1 hour of milling being somewhat larger than those for longer milling times, where submicron particles were formed. This was attributed to the presence of a larger fraction of molten B 2 O 3 compared to the longer-milled powders where TiBO 3 predominated.

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Section: Scanning Electron Microscopymentioning

confidence: 61%

Mechanical enhancement of the carbothermic formation of TiB2

Welham

2000

Metall Mater Trans A

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“…Oxygen content in particular need to be carefully controlled to balance the increase in hardness with decrease in ductility 4 . While many studies have experimentally measured [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] or computationally predicted [21][22][23][24] the diffusion of oxygen through various metal alloy systems, there is a lack of a fundamental atomistic understanding of how oxygen diffuses through many basic metal systems in a systematic manner.…”

Section: Introductionmentioning

confidence: 99%

Oxygen diffusion in hcp metals from first principles

Wisesa

Trinkle

2016

Phys. Rev. B

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Oxygen interstitial site energies and migration barriers in 15 HCP metals have been calculated with firstprinciples density functional theory. Multiple HCP systems show a preference for the hexahedral site over the tetrahedral site, as well as a stable crowdion site. More surprisingly, in more than half of the HCP systems, the oxygen does not choose the large octahedral interstitial as its ground-state. We explain this result based on the effective valence of the metal from crystal field splitting and the c/a ratio. Diffusion constants for oxygen in all 15 HCP systems are calculated from analytically derived diffusion equations and match available experimental data.

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“…From the Arrhenius equation, k p = (constant)AEexp()E a /RT), where R is 8.314 (J/mol-K) and T is the temperature (K),the activation energy for the oxidation of TiN-Ti 5 Si 3 , E a , was calculated to be 247.7 (kJ/mol). This value falls in the range of the reported E a values for the oxidation of Ti, i.e., 235-265 (kJ/mol) 19 .…”

Section: Resultsmentioning

confidence: 79%

High-Temperature Oxidation of TiN-Ti5Si3 Composites Prepared by Polymer Pyrolysis

Lee

Kim

2006

Oxid Met

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Composites consisting of a TiN matrix containing about 32 vol.% Ti 5 Si 3 were synthesized via polymer pyrolysis, and oxidized in the temperature range of 700 to 900°C for up to 120 h in air. Oxidation occurred mainly in the TiN matrix, because Ti 5 Si 3 was resistant to oxidation. The oxidation of the TiN matrix was preceded by the outward diffusion of Ti ions to form an outer TiO 2 layer, and the inward diffusion of oxygen ions to form an inner TiO 2 layer, together with nitrogen evolution from the TiN matrix.

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Literature Survey on Diffusivities of Oxygen, Aluminum, and Vanadium in Alpha Titanium, Beta Titanium, and in Rutile

Cited by 133 publications

References 26 publications

Mechanical enhancement of the carbothermic formation of TiB2

Mechanical enhancement of the carbothermic formation of TiB2

Oxygen diffusion in hcp metals from first principles

High-Temperature Oxidation of TiN-Ti5Si3 Composites Prepared by Polymer Pyrolysis

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