First-Principles Calculations and CALPHAD Modeling of Thermodynamics

Abstract

Thermodynamics is the key component of materials science and engineering. The manifestation of thermodynamics is typically represented by phase diagrams, traditionally for binary and ternary systems. Consequently, the applications of thermodynamics have been rather limited in multicomponent engineering materials. Computational thermodynamics, based on the CALPHAD approach developed in the last few decades, has released the power of thermodynamics and enabled scientists and engineers to make phase stability calculations routinely for technologically important engineering materials. Within the similar time frame, first-principles quantum mechanics technique based on density functional theory has progressed significantly and demonstrated in many cases the accuracy of predicted thermodynamic properties comparable with experimental uncertainties. In this paper, the basics of the CALPHAD modeling and first-principles calculations are presented emphasizing current multiscale and multicomponent capability. Our research results on integrating first-principles calculations and the CALPHAD modeling are discussed with examples on enthalpy of formation at 0 K, thermodynamics at finite temperatures, enthalpy of mixing in binary and ternary substitutional solutions, defect structure and lattice preference, and structure of liquid, super-cooled liquid, and glass.

Modeling of Some Physical Properties of Zirconium Alloys for Nuclear Applications in Support of UFD Campaign

“…Lukas et al [23], Saunders and Miedownik [24] developed the generalized equilibrium conditions, (software BINGGS for binary systems). Liu used first-principles approach to obtain data necessary for thermodynamic simulations, [25]. Similar work developed, concurrently and independently, in Canada (A.D. Pelton and software FactSage) and in the US (the late Prof. Austin Chen, software PANDAT).…”

Prediction and characterization of heat-affected zone formation in tin-bismuth alloys due to nickel-aluminum multilayer foil reaction

“…(10)) has been used extensively to model temperature and composition dependent properties for solution phases. [28][29][30] This methodology was chosen due to its ability to provide a consistent means to model all of the properties of interest. Additionally, this approach can be easily expanded and applied to more complex systems (i.e., ternary systems and beyond), which allows for greater utility in the future.…”

Phase-field Model for Interstitial Loop Growth Kinetics and Thermodynamic and Kinetic Models of Irradiated Fe-Cr Alloys

“…Since the radiation defects (vacancies and interstitials) occupy the host and interstitial lattices, a general two-sublattice thermodynamic model with multi-components can be used to describe the enthalpy and entropy changes for the alloy system. 51,52 The second term on the right side of Eq. (1) is the gradient energy associated with the interfacial energy of the interstitial loops.…”

“…In this case, the sublattice free energy formulism has been extensively used in thermodynamic calculations such as CALPHAD. 52 We suggest using the two-sublattice model shown in Figure 8 to describe the irradiated Fe-Cr alloys. In the ln , (25) where the first summation goes over all sublattices and the second summation goes over all constitutions in the corresponding sublattice.…”