Thermodynamic modeling of the NbeB system

Rockfeller Maciel Peçanha (1) , Flàvio Ferreira (2) , Gilberto Carvalho Coelho (1) , Carlos Angelo Nunes (1) , Bo Sundman (3)

1 USP - Universidade de São Paulo = University of São Paulo
2 UFF - Universidade Federal Fluminense [Rio de Janeiro]
3 KTH - KTH Royal Institute of Technology [Stockholm]

In the present work, the Nb-B binary system was thermodynamically optimized. The stable phases in this system are BCC (niobium), Nb3B2, NbB, Nb3B4, Nb5B6, NbB2, B (boron) and liquid L. The borides Nb3B2, NbB, Nb3B4 and Nb5B6 and the B (boron) were modeled as stoichiometric phases and the liquid L, BCC (niobium) and NbB2 as solutions, using the sublattices model, with their excess terms described by the Redlich-Kister polynomials. The Gibbs energy coefficients were optimized based on the experimental values of enthalpy of formation, low temperature specific heat, liquidus temperatures and temperatures of invariant transformations. The calculated Nb-B diagram reproduces well the experimental values from the literature.

Mots clés: A. Intermetallics; miscellaneous; B. Phase diagrams; B. Thermodynamic and thermochemical properties; E. Phase diagram; prediction

Domaines: Matériaux

Rockfeller Maciel Peçanha, Flàvio Ferreira, Gilberto Carvalho Coelho, Carlos Angelo Nunes, Bo Sundman. Thermodynamic modeling of the NbeB system. Intermetallics, 2007, vol. 15, pp.999-1005. ⟨10.1016/j.intermet.2006.10.054⟩. ⟨hal-00806040⟩