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The thermodynamic optimization of the Sn-Y and Mg-Sn-Y systems was critically carried out by means of the CALPHAD (CALculation of PHAse Diagram) technique. In the Sn-Y system, the solution phases (liquid, bcc, bct and hcp) were described by the substitutional solution model. The compound Sn 3 Y 5 , which has a homogeneity range, was treated as the formula (Sn, Y) 3 (Sn, Y) 2 Y 3 by a three-sublattice model in accordance with the site occupancies. In the Mg-Sn-Y system, the liquid phase was treated as the formula (Mg, Sn, Y, Mg 2 Sn) using an associated solution model, and bcc, bct and hcp were treated as the formula (Mg, Sn, Y). The compound Sn 3 Y 5 was treated as the formula (Sn, Y, Mg) 3 (Sn, Y, Mg) 2 Y 3 . The ternary compound MgSnY was treated as stoichiometric compound. A set of self-consistent thermodynamic parameters of the Mg-Sn-Y system was obtained. The projection of the liquidus surfaces and the reaction scheme of the Mg-Sn-Y system were predicted.

The Fe−Y and the Fe−Ni−Y systems were assessed by means of the CALPHAD (CALculation of PHAse Diagram) technique. The solution phases, liquid, bcc, fcc and hcp, were described by the substitutional solution model. The binary compounds, Fe17Y2, Fe23Y6, Fe3Y, Fe2Y, Ni17Y2, Ni5Y, Ni4Y, Ni7Y2, Ni3Y, Ni2Y, NiY, Ni2Y3 and NiY3, were treated as stoichiometric compounds. In the Fe−Ni−Y system, the intermetallic compounds were treated as the line compounds (Fe,Ni) m Y n by a two-sublattice model. A self-consistent thermodynamic description of the Fe−Ni−Y system was obtained.

The thermodynamic properties of the Co–Ni–Y system have been analyzed by means of the CALPHAD technique. The solution phases (liquid, body-centered cubic, face-centered cubic and hexagonal close-packed) were modeled with the Redlich–Kister equation. The line intermetallic compounds (Co,Ni) 17 Y 2 and (Co,Ni) 5 Y were treated as one phase with the formula (Co 2 ,Ni 2 ,Y)(Co 2 ,Y) 2 (Co,Ni) 15 , based on their crystal structures, by a three-sublattice model with Co 2 , Ni 2 , and Y on the first sublattice, Co 2 and Y, and Co and Ni on the second and third one, respectively. The other intermetallic compounds were treated as the line compounds (Co,Ni) m Y n by a two-sublattice model with Co and Ni on the first sublattice, Y on the second one, respectively. A self-consistent thermodynamic description of the Co–Ni–Y system was obtained.

The Au–Pr system was critically assessed by means of the CALPHAD technique. The solution phases (liquid, body-centered cubic (Pr), face-centered cubic (Au) and double hexagonal close-packed (Pr)) were modeled with the Redlich–Kister equation. Seven intermetallic compounds, Au6Pr, Au51Pr14, Au36Pr17, Au2Pr, Au4Pr3, AuPr and AuPr2, in the Au–Pr system were treated as stoichiometric compounds. A set of self-consistent thermodynamic parameters of the Au–Pr system was obtained.