The influence of the icosahedral percolation transition in supercooled liquid iron on the diffusion mobility of atoms
| Autor: | Alexander V. Evteev, A. T. Kosilov, O. B. Logachev, Elena V. Levchenko |
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| Rok vydání: | 2005 |
| Předmět: | |
| Zdroj: | Journal of Experimental and Theoretical Physics. 101:521-527 |
| ISSN: | 1090-6509 1063-7761 |
| DOI: | 10.1134/1.2103221 |
| Popis: | The paper develops concepts of the structure of pure amorphous metals and atomic mechanisms of its formation. It is shown that a stable percolation cluster of interpenetrating and contacting icosahedra whose vertices and centers are occupied by atoms is formed under the conditions of isothermal annealing of instantaneously supercooled iron melt only below the critical temperature ∼1180 K identified with the glass transition temperature. The duration of isothermal annealing up to the formation of the icosahedral percolation cluster does not exceed ∼1.5 × 10−11 s at 900–1180 K. The time of the beginning of homogeneous nucleation was found to be minimum at the critical temperature above which stable icosahedral percolation cluster did not form. Arguments are provided in favor of the assumption that the formation of icosahedral percolation cluster interferes with the beginning of crystallization. A quantitative model is suggested to describe the diffusion mobility of atoms in metallic glasses. In this model, the mean-square displacement of atoms is represented as the sum of the contributions of the linear (Einstein) and logarithmic components. The latter appears because of irreversible structural relaxation. The icosahedral percolation transition was shown to change the activation parameters of the model jumpwise. |
| Databáze: | OpenAIRE |
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