Intrinsic self-diffusion and substitutional Al diffusion in {alpha}-Ti
- Univ. Muenster (Germany). Inst. fuer Metallforschung
- Chalmers Univ. of Technology, Goeteborg (Sweden). Physics Dept.
- Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering
Self-diffusion and Al impurity diffusion were studied in the {alpha} (h.c.p.) phase of Ti. The authors used four Ti materials with different impurity convents, including ultrapure Ti with extremely small concentrations of interstitial impurities (Fe, Co and Ni). The self-diffusion measurements are performed with the radiotracer {sup 44}Ti and the ion beam sputtering technique. For Al diffusion measurements in-depth profiling by secondary ion mass spectrometry is applied. The measurements are made both {perpendicular} and {parallel} to the c axis using single crystals and coarse-grained polycrystals. The measurements on ultrapure {alpha}-Ti yield the Arrhenius parameters D{sub 0{perpendicular}} = 1.35 {times} 10{sup {minus}3} m{sup 2}/s and Q{sub {perpendicular}} = 303 {+-} 2 kJ/mol for self-diffusion and D{sub 0{perpendicular}} = 6.6 {times} 10{sup {minus}3} m{sup 2}/s and Q{sub {perpendicular}} = 329 {+-} 2 kJ/mol for Al diffusion. The anisotropy factor D{sub {parallel}}/D{sub {perpendicular}} {approx} 0.5 for self-diffusion and {approx} 0.65 for Al diffusion. These results are treated as intrinsic diffusion properties of {alpha}-Ti. It is demonstrated that they are well consistent with the normal diffusion behavior in other h.c.p. metals. The authors conclude that both self-diffusion and substitutional solute diffusion in {alpha}-Ti are intrinsically normal and dominated by the vacancy mechanism. Diffusion in less pure {alpha}-Ti occurs faster and with a smaller activation energy. This effect is explained by the enhancement of atomic mobility in the matrix material owing to the interstitially dissolved fast-diffusing impurities.
- OSTI ID:
- 554115
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 10 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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