Enthalpies of formation of borides of iron, cobalt, and nickel by solution calorimetry in liquid copper

Abstract

The enthalpies of formation at 1385 ±2 K of the following crystalline borides have been determined by high temperature solution calorimetry using liquid copper as the calorimetric solvent. Fe2B-67.87 ±8.05 kJ mol−1, Co2B -58.1 ±7.0 kJ mol−1, Ni2B -67.66 ±4.12 kJ ml−1, FeB-64.63 ±4.34 kJ mol−1, CoB -69.52 ±6.0 kJ mol−1, and NiB -40.2 ±3.77 kJ mol−1. The enthalpy of fusion of NiB has been determined to be 28.25 ±1.54 kJ mol−1 at its melting point of 1315 K. New data are reported also for the enthalpies of solution of iron, cobalt, and nickel in copper, and for the enthalpies of interaction between these metals and boron in dilute solutions in liquid copper.