Thermodynamic re-optimizations of the Ru-X (X=Al, Hf, Mo, Ti) binary systems

The Ru-X (X = Al, Hf, Mo, Ti) systems were re-optimized by means of the CALPHAD method according to the experimental phase equilibria and thermochemical data, as well as updated Gibbs energy function of "GBCCRU" in SGTE Pure 5 database. The substitutional solution model was applied to the phases liquid, fcc_A1, bcc_A2 and hcp_A3. Besides, the phases Al6Ru, Al13Ru4, Al5Ru2, Al2Ru and Al3Ru2 in the Ru-Al system were modeled as stoichiometric compounds and the phase Mo5Ru3 (sigma) in the Ru-Mo system was described as (Mo,Ru)(10)(Mo,Ru)(20) and (Mo,Ru)(10)(Mo,Ru)(4)(Mo,Ru)(16) using the two-sublattice and three-sublattice models, respectively. The phases AlRu, HfRu and RuTi with the bcc_B2 crystal structure were treated as the ordered ones of bcc_A2. The reliable thermodynamic parameters of these binary systems were obtained, which could be used as the basis for thermodynamic calculations of high-order systems and database establishment of Ni-based superalloys.