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Computational thermodynamics

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Computational thermodynamics is the use of computers to simulating thermodynamic problems specific to materials science, particularly used in the construction of phase diagrams. Several open and commercial programs exist to perform these operations. The concept of the technique is minimization of Gibbs free energy of the system; the success of this method is due not only to properly measuring thermodynamic properties, such as those in the list of thermodynamic properties, but also due to the extrapolation of the properties of metastable allotropes (see Allotropy) of the chemical elements.

History

The computational modeling of metal-based phase diagrams, which dates back to the beginning of the previous century mainly by Johannes van Laar and to the modeling of regular solutions, has evolved in more recent years to the CALPHAD (CALculation of PHAse Diagrams). This has been pioneered by American metallurgist Larry Kaufman since the 1970s.[1][2][3]

Current state

Currently, computational thermodynamics may be considered a part of materials informatics and a cornerstone of the materials genome project and concepts. The de facto state of many concepts and software of computational thermodynamics refers to the activities of the SGTE Group, a consortium devoted to the development of thermodynamic databases; the open elements database is freely available[4] based on the paper by Dinsdale.[5] This so-called "unary" system proves to be a common basis for the development of binary and multiple systems and is exploited by both commercial and open softwares of this field. However, as recent CALPHAD papers and meetings state, while it is useful to keep a common base like the Dinsdale/SGTE database, there is a serious possibility that in the future some corrections of the common database will be needed. In such a case, probably most of the published assessments will have to be revised, like rebuilding an house changing its cornerstones. This concept have been depicted as one "inverted pyramid" :[6]. The mere extension of current approach - limited to temperatures above room temperature - proves to be a complex task.[7] PyCalpahd, a Python library is available to make simple computational thermodynamics calculation using open source code.[needs context][8] The application of CALPHAD to high pressure in some important applications, which are not restricted to one side of materials science such as the Fe-C system,[9] confirms experimental results by means of computational thermodynamic calculations of phase relations in the Fe–C system at high pressure. Zhang et al. considered viscosity and other physical parameters, which are beyond the domain of thermodynamics.[10]

Future developments

There is still a gap between ab initio methods[11] and operative computational thermodynamics databases; in the past, a simplified approach introduced by the early works of Larry Kaufman, based on Miedema's Model, was employed to check the correctness of even the simplest binary systems. However, relating the two communities to Solid State Physics and Materials Science remains a challenge,[12] as it has for many years.[13] Promising results from ab-initio quantum mechanics molecular simulation packages like VASP - Vienna Ab-initio Simulation Package are readily integrated in thermodynamic databases with approaches like Zentool.[14]

See also

References

  1. ^ L Kaufman and H Bernstein, Computer Calculation of Phase Diagrams, Academic Press N Y (1970) ISBN 0-12-402050-X[page needed]
  2. ^ N Saunders and P Miodownik, Calphad, Pergamon Materials Series, Vol 1 Ed. R W Cahn (1998) ISBN 0-08-042129-6[page needed]
  3. ^ H L Lukas, S G Fries and B Sundman, Computational Thermodynamics, the Calphad Method, Cambridge University Press (2007) ISBN 0-521-86811-4[page needed]
  4. ^ http://www.crct.polymtl.ca/sgte/unary50.tdb[full citation needed]
  5. ^ Dinsdale, A.T. (1991). "SGTE data for pure elements". Calphad. 15 (4): 317–425. doi:10.1016/0364-5916(91)90030-N.
  6. ^ http://web.micress.de/ICMEg1/presentations_pdfs/Hallstedt.pdf[full citation needed]
  7. ^ http://thermocalc.micress.de/proceedings/proceedings2015/tc2015_tumminello_public.pdf[full citation needed]
  8. ^ Otis, Richard; Liu, Zi-Kui (2017). "Pycalphad: CALPHAD-based Computational Thermodynamics in Python". Journal of Open Research Software. 5. doi:10.5334/jors.140.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  9. ^ Fei, Yingwei; Brosh, Eli (2014). "Experimental study and thermodynamic calculations of phase relations in the Fe–C system at high pressure". Earth and Planetary Science Letters. 408: 155–62. Bibcode:2014E&PSL.408..155F. doi:10.1016/j.epsl.2014.09.044.
  10. ^ Zhang, Fan; Du, Yong; Liu, Shuhong; Jie, Wanqi (2015). "Modeling of the viscosity in the AL–Cu–Mg–Si system: Database construction". Calphad. 49: 79–86. doi:10.1016/j.calphad.2015.04.001.
  11. ^ P. Turchi AB INITIO AND CALPHAD THERMODYNAMICS OF MATERIALS https://e-reports-ext.llnl.gov/pdf/306920.pdf
  12. ^ J. A. Alonso and N. H. March Electrons in Metals and Alloys http://www.sciencedirect.com/science/book/9780120536207[page needed]
  13. ^ https://www.elsevier.com/books/proceedings-of-the-international-symposium-on-thermodynamics-of-alloys/miedema/978-1-4832-2782-5[full citation needed][page needed]
  14. ^ http://zengen.cnrs.fr/manual.pdf[full citation needed]

University Courses on Computational Thermodynamics

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