Application of physical-empirical models to calculate a fragment of the phase diagram and the physical properties of BCC Fe–Cr alloys: I. Formulation of a model and the estimation and approximation of experimental data

• Published in: Russian metallurgy Metally 2015-03, Vol.2015 (3), p.237-243
• Main Authors: Udovskii, A. L., Vasil’ev, D. A.
• Format: Article
• Language: English
• Subjects: Alloys; Approximation; Chemistry and Materials Science; Electronics; Intermetallic compounds; Materials Science; Mathematical analysis; Mathematical models; Metallic Materials; Solid solutions; Specific heat; Thermal expansion
• ISSN: 0036-0295; 1555-6255; 1531-8648
• DOI: 10.1134/S0036029515030106

An approach, which includes the application of physical-empirical models for describing the contributions to the Gibbs energy of mixing of solid solutions for binary systems, is formulated. The chemical contribution at zero temperature is represented as the difference between the chemical energy of mixing obtained by ab inito calculations and the elastic contribution of the energy of lattice distortions that is caused by the size factor, which takes into account the matrix atom displacements in the first-third coordination spheres with respect to impurity atoms. The vibrational contribution to the Gibbs energy of a solid solution is considered using the Debye model with allowance for anharmonicity in the Mie–Grüneisen approximation, the magnetic contribution to the Gibbs energy is considered using the Inden–Hillert–Jarl formalism, and the contribution of thermally excited electrons is considered using electronic specific heat. The experimental data on the Debye temperature, the Curie temperature, the average magnetic moment, Young’s modulus, the thermal expansion coefficient, and the electronic specific heat of ferromagnetic bcc Fe–Cr solid solutions are analyzed, and the approximation of these properties depending on the alloy composition is considered. The effect of temperature on the dimension factor is