Reassessment of the Nb-Sn system

A new assessment of the Nb-Sn system is proposed considering the Nb3Sn phase stable down below room temperature. The Gibbs energy of formation of the solution and compound phases in the Nb-Sn system were derived from an optimization procedure using all the available experimental thermodynamic and phase diagram data. In particular, the enthalpy of formation of the Nb3Sn phase at 1350 degreesC was determined experimentally in this study. The thermodynamic description of the intermetallic compounds was made using a sublattice model, while a Redlish-Kister polynomial was used for the solution phases.