A thermodynamic description of the Gd-Mg-Sm system

作者：Guo Cuiping; Du Zhenmin^*; Li Changrong

来源：CALPHAD-COMPUTER COUPLING OF PHASE DIAGRAMS AND THERMOCHEMISTRY, 2010, 34(1): 90-97.

DOI：10.1016/j.calphad.2009.12.006

• Gd-Mg-Sm system
• CALPHAD technique
• Order-disorder transition

The Mg-Sm, Gd-Sm and Gd-Mg-Sm systems were thermodynamically optimized using the CALPHAD technique. The solution phases, liquid, bcc, hcp and rhombohedral, were described by the substitutional solution model. The isostructural compounds, MgGd in the Gd-Mg system and MgSm in the Mg-Sm system with a 82 structure was assumed to form a continuous range of solid solutions in the Gd-Mg-Sm system. The order-disorder transition between the bcc solution with an A2 structure and compound Mg(Gd, Sm) with a B2 structure in the system has been taken into account and thermodynamically modeled. The other isostructural compounds Mg(5)Gd and Mg(5)Sm, Mg(3)Gd and Mg(3)Sm, Mg(2)Gd and Mg(2)Sm in the Gd-Mg-Sm system were described according to the formulae Mg(5)(Gd,Sm), Mg(3)(Gd,Sm), and Mg(2)(Gd,Sm), respectively. The compound Mg(41)Sm(5) with a homogeneity range was treated as a line compound Mg(41)(Gd, Sm)(5) in the Gd-Mg-Sm system. Based on the experimental data in the Mg-rich corner of the Gd-Mg-Sm system, a set of thermodynamic parameters describing the Gibbs energies of individual phases of the Gd-Mg-Sm system as functions of composition and temperature was obtained. In addition, the complete ternary phase diagram of the Gd-Mg-Sm system were predicted.

• 出版日期2010-3
• 单位北京科技大学