A thermodynamic assessment of the iron–lead binary system

The thermodynamic properties and phase equilibria of the Fe–Pb binary system were assessed using the CALPHAD (CALculation of PHAse Diagrams) method based upon available literature data and results of isothermal equilibration experiments reported in this paper. The phase diagram and excess Gibbs energy values of the solution phases, namely the molten alloy and the γ-fcc and α- and δ-bcc solid solutions were expressed using Redlich–Kister polynomials. The experimental data were fitted by a least squares method using the MTDATA software. Agreement between experimental and calculated values is good. In particular the description of the solubility of lead in iron below the monotectic temperature has been improved.

• Isothermal equilibration experiments of the Fe–Pb binary were conducted in a special quartz ampoule and analyzed with ICP and EPMA.
• The method enables to obtain two experimental points from each end of the phase diagram in one experiment.
• New experimental data of the Pb solubility to Fe(s) below the monotectic temperature was obtained.
• This study consists of the widest critical compilation of the literature data done of the Fe–Pb binary system done so far, corrected also some errors in previous assessments.
• More accurate thermodynamic description of the Fe–Pb binary and its phases were obtained.