LAUSR

The analytic expressions for the free energy, the concentration of equilibrium vacancies, the isothermal compressibility, the thermal expansion coefficient and the heat capacities at constant volume and at constant pressure of BCC substitutional alloy AB with interstitial atom C and with vacancy under pressure are derived by the statistical moment method. The theoretical results are applied to the thermal expansion coefficient of alloy FeCrSi in the interval of temperature from 700 K to 1100 K, in the interval of substitutional atom concentration from 0% to 10%, in the interval of interstitial atom concentration from 0% to 5% and in the interval of pressure from 0 GPa to 10 GPa. Our calculated results for main metal Fe are compared with the experimental data.