The Phase Stability in the Fe-B Binary System: Comparison between the Interstitial and Substitutional Models

Abstract

In the present work, a thermodynamic study was carried out in order to analyze the thermodynamic stability of the and phases in equilibrium with the phase using the calculation of phase diagrams (Calphad) formalism. The two phases and are modelled as substitutional and interstitial solid solutions of boron. The expressions of the chemical potentials ofBandFeare derived in both phases to perform the thermodynamic calculations. A comparison is made between the results provided by the substitutional and interstitial models and good agreement is observed between these two models.

Grain-boundary segregation of boron in high-strength steel studied by nano-SIMS and atom probe tomography

“…This value is in good agreement with the Fe 2 B compound solubility in austenite, corresponding to X = exp( −67,375 J.mol −1 / RT −2.8763), i.e. H diss = + 0.7 eV [56] . Correlatively, the excess number also increases with increasing temperature ( Fig.…”

A Simple Kinetic Model for the Growth of Fe2B Layers on AISI 1026 Steel During the Powder-pack Boriding

“…The term B ads C is the effective adsorbed boron concentration during the boriding process [23]. From Figure 1 − is the miscibility gap and C 0 is the boron solubility in the matrix considered as null [24].…”

Boriding kinetics of Fe2B layers formed on AISI 1045 steel

“…The flux Jh -ej: and JF a are obtained from the Fick's First law as: The term JFe is null since the boron solubility in the matrix is very low ( * 0 mol n r3) [18,19].…”

“…From Figure 1, ax =C'£ defines the homogeneity range of the Fe2B layer,o2 = -C0 is the miscibility gap and C0 is the boron solubility in the substrate. The diffusion zone underneath the Fe2B layer can be ignored by setting (C0 a 0 mol m 3) [18,19].…”