Thermodynamic Properties of Magnesium-Boron Binary Alloys Determined Using Solid-State Electrochemical Measurements

This study provides the thermodynamic properties of the Mg-B binary alloys. Experiments were performed to measure the electromotive force (emf) as a function of temperature (773K to 873K) using a solid-state electrochemical cells that can be represented as (-)Pt, Ar/{Mg + CaF2 center dot MgF2}parallel to CaF2{Mg(alloy) + CaF2 center dot MgF2}/Ar, Pt(+) The activities of Mg in Mg-B alloys were calculated from the experimental emf data. The activity coefficients of Mg in Mg-B alloys were also determined. The integral Gibbs energies of formation (Gf degrees) of alloys were calculated from the activities of the Mg using tangent rule. The integral Gibbs energies of formation (Gf degrees) of MgB2, MgB4, and MgB7 are -15.48, -22.03, and -15.89kJ/mol-atoms at 873K.