| Autor: |
N. Lorenzelli, P. Convert, C. H. de Novion, V. Moisy-Maurice |
| Rok vydání: |
1982 |
| Předmět: |
|
| Zdroj: |
Acta Metallurgica. 30:1769-1779 |
| ISSN: |
0001-6160 |
| DOI: |
10.1016/0001-6160(82)90093-1 |
| Popis: |
High temperature neutron diffraction experiments on TiC1−x samples have allowed to determine from the thermal dependence of the (1/2 1/2 1/2), (3/2 1/2 1/2) and (3/2 3/2 1/2) superlattice reflexions the transition temperatures due to long-range ordering of carbon vacancies: 765° ± 5°C for TiC0.58. 785° ± 5°Cfor TiC0.63and 770° ± 5°Cfor TiC0.67. For the first composition, the transition is practically of second order type with a critical coefficient β = 0.26 ± 0.03, suggesting predominant short-range interactions between carbons and vacancies. A preliminary study of the kinetics of longrange ordering was performed between 650° and 750°C for TiC0.63: at 735°C, the average ordered domain size D increases with time t as D3.24 − D30240 ∼- Ct; the process is thermally activated with an apparent activation energy of 3.7± 0.2 eV. The kinetics of ordering decrease rapidly with increasing carbon content. The results are discussed in terms of recent theories of order-disorder and antiphase domain coarsening in alloys. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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