Influence of Liquid-Glass Transition on Diffusion and Nucleation in Computer-Simulated Iron

Abstract:

A molecular dynamic model for instantaneously undercooled iron melt has been applied to model the isothermal annealing of the stable percolation clusters. They contain mutual penetrating and contacting icosahedra with atoms at the vertices and centers. Such stable clusters form only below the critical temperature Tg ~1180 K. We identify Tg as the glass transition temperature. It is established that the time when a homogeneous nucleation starts is minimal for Tg. The stable icosahedral percolation clusters do not form above Tg. The proposed quantitative model describes the atomic mobility in metal glasses, where root-mean-square atomic displacement is the sum of contributions from both linear (Einsteinian) and logarithmic terms, associated to irreversible structure relaxation. The activation parameters of the model change abruptly at the icosahedral percolation transition.

• Periodical: Defect and Diffusion Forum (Volume 249)
• Pages: 97-104
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.249.97
• Online since: January 2006
• Authors: Alexander V. Evteev, A.T. Kosilov, Elena V. Levchenko, O.B. Logachev
• Keywords: Glass Transition, Molecular Dynamic (MD), Nucleation, Self-Diffusion

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[15] G.A. Korn and T.M. Korn: Mathematical Handbook for Scientists and Engineers (McGrawHill, N. Y. 1967) Discussion H. Mehrer: First, let me say that in my opinion you presented a very nice piece of work. My question is, whether you are aware of experimental work that demonstrates the existence of icosahedral clusters in metallic glasses? E. Levchenko: Thank you very much for your interest. I know such work [W.L. Luo, H.W. Sheng, F.M. Alamgir, J.M. Bai, J.H. He, E. Ma. Icosahedral Short-Range Order in Amorphous Alloys: Phys. Rev. Lett. Vol. 92 (2004).

DOI: 10.1103/physrevlett.92.145502