Investigation of formation mechanism and thermodynamic functions of Fe5B3 iron boride

Abstract

It is revealed that in Fe-B system alloys with boron content of 9.0–15.0 % (wt.) the formation of Fe5B3 iron boride is possible. The mechanism of formation and the temperature interval of existence of Fe5B3 iron boride in Fe-B system alloys are determined. Such thermodynamic quantities of Fe5B3 iron boride as entropy, enthalpy, heat capacity and their temperature dependence are considered. It is shown that accounting for the first degree approximation of high-temperature expansion of the thermodynamic potential of binary Fe-B alloy in the Hillert and Staffansson model enables to give more complete description of appearing of Fe5B3 boride from the thermodynamic viewpoint.