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Effects of ballistic atom movements on ordering transitions of binary alloys

Hong, L. B. and Fultz, B. (1995) Effects of ballistic atom movements on ordering transitions of binary alloys. Physical Review B, 51 (5). pp. 2687-2693. ISSN 0163-1829. http://resolver.caltech.edu/CaltechAUTHORS:HONprb95a

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Abstract

We studied chemical order-disorder transitions in equiatomic alloys on a square lattice in the presence of both thermal and ballistic atom movements. Using Monte Carlo simulations with a vacancy mechanism, we determined the steady states of the alloys for various combinations of f (fraction of ballistic atom movements) and T (temperature), and located the order-disorder phase boundary on a diagram of T vs f. For symmetric interatomic potentials, the dynamical critical temperature decreased with f as (1-1.58f) when f≤0.36, and decreased rapidly with f when 0.36<f≤0.43. No ordered phase was stable at any temperature when f was greater than a critical value of fc0>0.43. An Onsager-type kinetic rate equation was modified to include ballistic atom movements, and was used to identify two reasons why the ballistic atom movements suppress the dynamical critical temperature: (1) the ballistic atom movements dilute the enthalpy driving force for ordering, and (2) at low temperatures the ratio of thermal mobility coefficient to ballistic mobility coefficient becomes small.


Item Type:Article
Additional Information:©1995 The American Physical Society Received 29 August 1994 We thank Professor W. L. Johnson and Dr. L. Anthony for useful discussions. This work was supported by NSF under Contract No. DMR-9213447.
Record Number:CaltechAUTHORS:HONprb95a
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:HONprb95a
Alternative URL:http://dx.doi.org/10.1103/PhysRevB.51.2687
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1798
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:18 Feb 2006
Last Modified:26 Dec 2012 08:46

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