MIXING ENTHALPY AND HEAT-CONTENT MEASUREMENTS OF LIQUID BINARY IRON NIOBIUM ALLOYS

The mixing enthalpy of the system iron-niobium has been determined at 1935 and 2035 K for alloys having Nb mass contents of up to 51.5% by the levitation alloying calorimetry (LAG). Moreover, by means of the combination of an electromagnetic levitation unit with a drop calorimeter the temperature functions of the enthalpies of the eutectic alloys Fe89.4Nb10.6 and Fe41Nb59 and the congruent melting compound Fe2Nb have been measured in the liquid state and below their melting points. From these Values the melting enthalpies and entropies are calculated. The experimental results are compared with literature data. In consideration of the standard formation enthalpy of the alloys their enthalpy values could be connected with the mixing enthalpy.