Дослідження термодинамічних функцій бориду заліза \[\textrm{Fe}_{2}\textrm{B}\

Abstract

Background. The alloys of Fe-B system find wide application because of a complex of unique physical properties, but in the literature there is no information about thermodynamic functions of phases for these alloys with accounting for the contributions, which are responsible for fluctuation processes description. Objective. Objective of the paper is to study the physical properties and thermodynamic functions of boride Fe 2 В, and their temperature dependence with accounting for the zeroth-order approximation for high-temperature expansion of thermodynamic potential for Fe-В system binary alloys. Methods. Investigation was performed for Fe-В system alloys with boron content of 9,3–15,0 % (wt.),the rest is iron. We use the microstructure, X-ray structural and calorimetric analysis to ascertain the physical properties of alloys. Results. The phase composition of Fe-В alloys and physical properties of Fe 2 В boride is determined and temperature dependence of heat capacity for Fe-В alloys is obtained. The thermodynamic functions for Fe 2 В boride and their temperature dependence are calculated by means of Hillert and Staffonsson model with accounting for the zeroth-order approximation for high-temperature expansion of thermodynamic potential for Fe-В system binary alloys. Conclusions. The temperature dependence of entropy, enthalpy and heat capacity С р of iron boride Fe 2 B in binary Fe-B alloy is obtained for the first time on the basis of Hillert and Staffonsson model with accounting for the zeroth-order contribution of high-temperature expansion of thermodynamic potential. The temperature of iron boride formation is calculated and it agrees with Fe-B diagram data.