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Descripción
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| The interaction between dislocations and Guinier-Preston zones in an Al-Cu alloy was analyzed using different atomistic approaches. The different thermodynamic functions that determine the features of these barriers were computed using molecular statics, molecular dynamics, and the nudged elastic band method. It was found that Guinier-Preston zones are cut by dislocations and the rate at which dislocations overcome the precipitate is controlled by the activation free energy, dG (s), in agreement with the postulates of the transition state theory. However, its harmonic approximation (HTST) does not hold for this interaction. The Helmholtz activation free energy, dF, the activation volume, (V0), the activation entropy, dS(T, s), and variation of internal energy, dU(s), were determined as a function of the stress. It was found that both, dS(T,s) and dU (s), decrease when the stress increases as reported in previous studies, with values for the activation volume also in agreement. Finally, an estimation of the initial shear flow stress as a function of temperature was carried out from the thermodynamic data provided by the atomistic simulations. Some discrepancies between the experimental results and our predictions were found and rationalized in terms of the precipitate distribution and dislocation character. | |
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Internacional
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Si |
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Nombre congreso
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CNLS 38th Annual Conference: Rate Theory and Long Time scale Simulations |
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Tipo de participación
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960 |
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Lugar del congreso
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Santa Fe, New Mexico, US |
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Revisores
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ISBN o ISSN
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DOI
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Fecha inicio congreso
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29/05/2018 |
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Fecha fin congreso
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02/06/2018 |
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