First principle energies of binary and ternary phases of the Fe–Nb–Ni–Cr system

We present first principles enthalpies of formation and lattice parameters of iron, nickel, chromium and niobium alloys. Some of these results have been partially used in a recent assessment of the Fe–Ni–Cr–Nb quaternary phase diagram. Emphasis has been put on the fcc (A1) and bcc (A2) unary structures, the X3Y-D022, -L12, -D03, -D0a, X2Y-C14(MgZn2), -C15(MgCu2) and -C36 (MgNi2) Laves and X7Y6-D85 (μ) binary phases, and the X8Y4Z18-D8b (σ) ternary phase. We employed the state of the art to compute their properties by means of the DFT (PBE functional and PAW pseudo potentials). A comparison with experimental and theoretical data is also provided

First principle energies of binary and ternary phases of the Fe–Nb–Ni–Cr system

This is an author-deposited version published in: http://oatao.univ-toulouse.fr/ Eprints ID: 5546 To cite this version: Connétable, Damien and Mathon, Muriel and Lacaze, Jacques First principle energies of binary and ternary phases of the Fe-Nb-Ni-Cr system. (2011) Calphad, vol. 35 (n° 4 a b s t r a c t We present first principles enthalpies of formation and lattice parameters of iron, nickel, chromium and niobium alloys. Some of these results have been partially used in a recent assessment of the Fe-Ni-Cr-Nb quaternary phase diagram. Emphasis has been put on the fcc (A1) and bcc (A2) unary structures, the X 3 Y-D0 22 , -L1 2 , -D0 3 , -D0 a , X 2 Y-C14(MgZn 2 ), -C15(MgCu 2 ) and -C36 (MgNi 2 ) Laves and X 7 Y 6 -D8 5 (µ) binary phases, and the X 8 Y 4 Z 18 -D8 b (σ ) ternary phase. We employed the state of the art to compute their properties by means of the DFT (PBE functional and PAW pseudo potentials). A comparison with experimental and theoretical data is also provided

Calphad-type assessment of the FeNbNi ternary system

This paper presents a Calphad-type thermodynamic database for the FeNbNi system. The stable phases in this ternary system are liquid, fcc_A1, bcc_A2, C14 Laves, D0a, D85 and L12_fcc but we took also into account the C15 Laves and the metastable D022 phase because of their engineering interest. Available optimizations of the unary and binary systems were selected from the literature with the constraint that the Gibbs energy descriptions must be compatible. The only amendment needed to the selected assessments concerned the parameters for the D85 in the FeNb system. In addition, ab-initio calculations have been performed using the VASP in order to help with estimating enthalpies of formation of some binary end members of the intermetallic compounds. The optimization of the FeNbNi ternary system was performed using mostly experimental data available in the literature