On the Mg-Pb system. Calorimetric studies and thermodynamic calculations

In this paper, the experimentally determined integral and partial molar enthalpy of mixing of liquid Mg-Pb alloys is presented. Five separate measurements were performed at 1012 and 1014 K with the use of MHTC 96 Line Evo line drop calorimeter. The values of integral molar mixing enthalpy are characterized by negative deviations from the ideal solutions in the entire concentration range. Based on obtained results and other thermodynamic quantities available in the literature the Mg-Pb phase diagram was optimized. The calculated and experimentally obtained values of the integral molar mixing enthalpy are also compared with the Miedema model prediction of the integral molar mixing enthalpy. The formation enthalpy for the Mg2Pb phase is computed by ab initio calculations and equals -5978 J/mol of atoms at 0 K. For the Mg2Pb intermetallic phase, the calculated bulk isothermal and adiabatic modulus, as well as a variation of primitive cell volume and thermal expansion coefficient with the temperature, are presented. Moreover, the heat content of the Mg2Pb intermetallic phase is shown and compared with experimental data for temperatures from 0 K to its melting temperature. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This paper presents the experimentally determined molar enthalpy of mixing of liquid Mg-Pb alloys, compares the results with thermodynamic models, and optimizes the Mg-Pb phase diagram. Additionally, ab initio calculations were used to compute the formation enthalpy of Mg2Pb phase and analyze its thermodynamic properties and heat content.