Thermodynamic Assessments of the Al2O3-Al4C3-AlN and Al4C3-AlN-SiC Systems

A thermodynamic dataset for the Al₂O₃-Al₄C₃-AlN system was reassessed and that of the Al₄C₃-AlN-SiC system was developed in present study for the first time based on available literature data using the CALPHAD approach. In the Al₂O₃-Al₄C₃-AlN system and its subsystems the liquid was described as single phase using the partially ionic liquid model $ ({\text{Al}}^{3 + } )_{P} ({\text{Va,AlC}}_{3/4} ,{\text{AlO}}_{3/2} , {\text{AlN}},{\text{O}}^{2 - } ,{\text{N,C}})_{Q} $ , which covers compositions from the metallic liquid to the oxide, carbide and nitride liquids. The compound energy formalism was used for modeling of the solid phases in both studied systems. Ternary phases ?? and ?? of the Al₄C₃-AlN-SiC system were treated as stoichiometric compounds. A four sublattice model was proposed in order to describe the ??-solid solution forming between the isostructural Al₅C₃N and Al₄SiC₄ binary phases. Using the derived datasets the isothermal sections at 1600, 2273 and 2373?K for the Al₂O₃-Al₄C₃-AlN system and at 2133?K for the Al₄C₃-AlN-SiC system were constructed. The calculated phase diagrams of both ternary systems were compared with the available experimental data.     

Al-rich region of Al–Pd–Ru at 1000 to 1100 °C

Partial isothermal sections of the Al–Pd–Ru phase diagram at 1000, 1050 and 1100 °C are presented here. The Al–Pd orthorhombic -phases dissolve up to 15.5 at.% Ru, Al₁₃Ru₄ <2.5 at.% Pd and Al₂Ru up to 1 at.% Pd. Between 66 and 75 at.% Al, ternary quasiperiodic icosahedral phase and three cubic phases: C (, a = 0.7757 nm), C₁ (, a = 1.5532 nm) and C₂ (, a = 1.5566 nm) were revealed. An additional complex cubic structure with a ≈ 3.96 nm was found to be formed at compositions close to those of the icosahedral phase.