Berlin 2015 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 9: Hydrogen in metals II: Multiscale simulations

MM 9.4: Talk

Monday, March 16, 2015, 12:45–13:00, TC 006

The Role of Temperature on the Free Energy of Hydrogen in Iron. — •Robert Horton and Michael Finnis — Royal School of Mines, Imperial College, London

A key advance in the development of hydrogen resistant steels is the inclusion of defects (such as vacancies and carbides) within the steel matrix to act as traps for the hydrogen. The development of predictive mesoscopic models to aid in the design of these steels requires knowledge of the chemical potentials of hydrogen both in the bulk and within the traps as a function of temperature.The high concentrations and high mobility of hydrogen in these systems brings the validity of traditional atomistic approaches to the calculation of the free energy into question.

In recent years a number of Monte Carlo techniques have been developed [1,2] that allow the calculation of the full partition function and thus the free energy of the system. These techniques provide a promising route to calculating the free energy of systems containing high concentrations of defects [3].Through the application of these techniques to a system containing hydrogen in iron we show that they indeed allow one to calculate the free energy of such systems. Free energies calculated in this manner can then be included in mesoscale simulations.

[1]Wang, Fugao and Landau, D. P. (Mar 2001). Phys. Rev. Lett. (American Physical Society) 86 (10): 2050*2053. [2]Skilling, J.Bayesian Analysis 1, 833*860 (2006). [3]Horton, R. M. et al. Journal of Physics. Condensed matter 25, 395001 (2013).