In a preceding project, functional forms for “short” Helmholtz energy equations of state for typical nonpolar and weakly polar fluids and for typical polar fluids were developed using simultaneous optimization. In this work, the coefficients of these short forms for the equations of state have been fitted for the fluids acetone, carbon monoxide, carbonyl sulfide, decane, hydrogen sulfide, 2-methylbutane (isopentane), 2,2-dimethylpropane (neopentane), 2-methylpentane (isohexane), krypton, nitrous oxide, nonane, sulfur dioxide, toluene, xenon, hexafluoroethane (R-116), 1,1-dichloro-1-fluoroethane (R-141b), 1-chloro-1,1-difluoroethane (R-142b), octafluoropropane (R-218), 1,1,1,3,3-pentafluoropropane (R-245fa), and fluoromethane (R-41). The 12 coefficients of the equations of state were fitted to substance specific data sets. The results show that simultaneously optimized functional forms can be applied to other fluids out of the same class of fluids for which they were optimized without significant loss of a...

Short Fundamental Equations of State for 20 Industrial Fluids

Mathematical representation of thermodynamic properties: part ii. derivation of the combined nearly ideal binary solvent(nibs)/redlich-kister mathematical representation from a two-body and three-body interactional mixing model

The origin of the moon and the early history of the earth—A chemical model. Part 1: The moon

The degradation of austenitic stainless steels in a radiation environment is a known problem for the in-core components of nuclear light water reactors. For a better understanding of the prevailing mechanisms responsible for the materials' degradation, large-scale atomistic simulations are desirable. In this framework and as a follow-up on Bonny et al (2011 Modelling Simul. Mater. Sci. Eng. 19 085008), we developed an embedded atom method type interatomic potential for the ternary FeNiCr system to model the production and evolution of radiation defects. Special attention has been drawn to the Fe10Ni20Cr alloy, whose properties were ensured to be close to those of 316L austenitic stainless steels. The potential is extensively benchmarked against density functional theory calculations and the potential developed in our earlier work. As a first validation, the potential is used in AKMC simulations to simulate thermal annealing experiments in order to determine the self-diffusion coefficients of the components in FeNiCr alloys around the Fe10Ni20Cr composition. The results from these simulations are consistent with experiments, i.e., DCr > DNi > DFe.

https://iopscience.iop.org/article/10.1088/0965-0393/21/8/085004/pdf

Interatomic potential for studying ageing under irradiation in stainless steels: the FeNiCr model alloy

An overview of the thermophysical properties of segregating and demixing liquid binary alloys is presented encompassing the simple approaches that are commonly used by physicists, chemists and metallurgists in general. The various experimental and theoretical information available for such systems are put together to establish a respectable understanding between the experimental results, theoretical approaches and the empirical models. The key to understanding is the deviation that the properties exhibit from Raoult's law and the marked change in the liquid phase as a function of composition, temperature and pressure. The characteristic behaviour is ascribed to an outcome of the interplay of the energetic and structural re-adjustment of the constituent elements on mixing. After summarizing the experimental technique and some results, a comprehensive microscopic approach, based on statistical, electronic and hard sphere-like theory, is undertaken to further the understanding of the origin of the intriguing processes that are associated with the immiscible and phase-separating liquid alloys. We conclude by providing a brief account of the kinetic aspects of phase separation with some intended industrial applications.

https://iopscience.iop.org/article/10.1088/0034-4885/60/1/003/pdf

Segregation and immiscibility in liquid binary alloys

The equivalence of the Redlich-Kister expansion, and the Chebyshev polynomial expansion to power series in regard with the representation of thermodynamic excess properties is proved mathematically. Simple conversion formulas are derived for the computation of the coefficients of the power series, sk, from the parameters of the Redlich-Kister expansion, Bn, and from the parameters of the Chebyshev polynomial expansion, Al, and vice-versa. The essential feature of the proposed conversion procedures is the independence of the conversion coefficients b(n,k) and a(l,k) from the actual thermodynamic excess properties.

Mathematical conversions of the thermodynamic excess functions represented by the Redlich-Kister expansion, and by the Chebyshev polynomial series to power series representations and vice-versa.☆

The system Fe–Ni–Cr: revision of the thermodynamic description

The unequivocalness of the Schmidt orthogonalization procedure causes necessary mathematical equivalence of Legendre polynomial expansions and simple power series for the approximation of thermodynamic functions. Simple conversion-formulas are derived for the determination of the coefficients α m of simple power series from the parameters A 1 of Legendre polynomial expansions as well as for calculation of trie parameters A 1 from the power-series-coefficients α m . The derived conversion procedures are independent from the regarded curve.

Zur konversion der anpassungen thermodynamischer funktionen mittels einer reihe legendre'scher polynome und der potenzreihe

Strict algebraic evaluation of experimental thermodynamic excess data yields necessarily consistant values of the excess functions H E , S E , and G E . The thermodynamically adapted power (T.A.P)-series may be the most profitable expansion to represent the molar partial and integral excess functions of binary and ternary systems. Detailed expressions of the corresponding approximation formulas are enclosed.

Josef Tomiska

Papers

Mathematical conversions of the thermodynamic excess functions represented by the Redlich-Kister expansion, and by the Chebyshev polynomial series to power series representations and vice-versa.☆

The system Fe–Ni–Cr: revision of the thermodynamic description

Zur konversion der anpassungen thermodynamischer funktionen mittels einer reihe legendre'scher polynome und der potenzreihe

On the modern algebraic representation of general thermodynamic excess properties

Algebraische darstellung der therhodynamischeu mischungsfunktionen und ihre umrechnung: Teil I. Die approximationsgleichukgen