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New Approach to the Compound Energy Formalism (Nacef)Part Ii. Thermodynamic Modelling of the Al–Nb System Supported by First-Principles Calculations

2022; RELX Group (Netherlands); Linguagem: Inglês

10.2139/ssrn.4141217

1556-5068

J.M. Fiorani, M. Badran, Jean‐Marc Joubert, Jean‐Claude Crivello, Antonio Augusto Araújo Pinto da Silva, Gilberto Carvalho Coelho, Carlos Ângelo Nunes, Nicolás David, M. Vilasi,

Thermodynamic and Structural Properties of Metals and Alloys

In the present work, a new assessment of the Al–Nb system, using a combined first-principle and CALPHAD approach, is presented. Formation enthalpies of all ordered configurations of the intermetallic phases (s, D 0 22 and A 15) were estimated from ab initio calculations. The liquid, fcc and bcc phases are described by a substitutional solution model. In first, s phase was described with the five-sublattice (5SL) model using combined CEF model where a modification was applied which allows to respect the formation enthalpies of end-members obtained from ab initio calculations. Then, a comparison of the results obtained using a simplified two-sublattice (2SL) model for the s phase is presented, which only highlights slight differences with the full description. The intermetallic phases, D 0 22 , A 15 and s based on the simplified two-sublattice model are described with the New Approach to the Compound Energy Formalism (NACEF). In both cases, assessments derived from 5SL and 2SL descriptions of s phase show very good agreement with the available experimental and ab initio data with a limited number of used parameters. In this sense, self-consistent thermodynamic descriptions of the Al–Nb system is provided. Moreover, this work shows from the example of the σ phase that the NACEF approach, contrary to what is commonly considered, allows the compatibility between different descriptions using different numbers of sublattices. This is particularly interesting for the construction of multi-component databases.