Please use this identifier to cite or link to this item: https://apo.ansto.gov.au/dspace/handle/10238/7523
Title: The thermodynamics of hydride precipitation: The importance of entropy, enthalpy and disorder
Authors: Lumley, SW
Grimes, RW
Murphy, ST
Burr, PA
Chroneos, A
Chard-Tuckey, PR
Wenmam, MR
Keywords: Zirconium hydrides
Thermodynamics
Precipitation
Entropy
Hydrides
Density functional methods
Issue Date: 15-Oct-2014
Publisher: Elsevier
Citation: Lumley, S. C., Grimes, R. W., Murphy, S. T., Burr, P. A., Chroneos, A., Chard-Tuckey, P. R., & Wenman, M. R. (2014). The thermodynamics of hydride precipitation: The importance of entropy, enthalpy and disorder. Acta Materialia, 79(0), 351-362. doi:10.1016/j.actamat.2014.07.019
Abstract: The precipitation of zirconium hydrides from Zr solid solution was investigated using first-principles lattice dynamics simulations. These included the temperature-dependent vibrational enthalpy and vibrational entropy combined with the configurational entropy terms. In contrast with previous approaches, it was found that the latent enthalpy alone is not sufficient to fully describe precipitation of hydrides; a full thermodynamic assessment is required. In particular, the vibrational enthalpy of precipitation assists in stabilizing hexagonal close-packed hydrides and is especially important in forming the metastable ζζ phase. The configurational entropy change during precipitation favours face-centred cubic hydrides. Given this, at concentrations below 300 ppm H, no hydride precipitation is predicted, suggesting that when hydrides are seen in those materials it is because the local concentration of H is greater than that measured globally. While γγ hydride is the most stable phase, it is very close in energy to the δδ phase. © 2014 Acta Materialia Inc.
Gov't Doc #: 7105
URI: http://dx.doi.org/10.1016/j.actamat.2014.07.019
http://apo.ansto.gov.au/dspace/handle/10238/7523
ISSN: 1359-6454
Appears in Collections:Journal Articles

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