Hantong Chen , Qi-Jun Hong , Alexandra Navrotsky , Axel van de Walle
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引用次数: 0
Abstract
The CALPHAD (CALculation of PHAse Diagram) framework relies heavily on the availability of a well-defined free energy for all possible phases, including metastable and even mechanically unstable phases. However, for phases that exhibit mechanical instability, the determination of the free energy represents a challenge, both experimentally and computationally. This situation hinders the seamless integration of experimental and ab initio thermodynamic data. A newly developed method, named “inflection-detection”, provides a practical computational solution to this problem with a sound theoretical basis. Extending upon existing energy calculations at absolute zero, we provide further evidence of this method’s effectiveness by computing the temperature-dependent free energy references for 22 elemental structures involving mechanically unstable phases and showing that they are reasonably consistent with the (often wide) range of values determined in earlier experimental assessments. This suggests the feasibility of a reliable computation-based reference free energy standard for mechanically unstable pure elements.
期刊介绍:
The design of industrial processes requires reliable thermodynamic data. CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) aims to promote computational thermodynamics through development of models to represent thermodynamic properties for various phases which permit prediction of properties of multicomponent systems from those of binary and ternary subsystems, critical assessment of data and their incorporation into self-consistent databases, development of software to optimize and derive thermodynamic parameters and the development and use of databanks for calculations to improve understanding of various industrial and technological processes. This work is disseminated through the CALPHAD journal and its annual conference.