Generalization of first-principles thermodynamic model: Application to hexagonal close-packed ε-Fe3N

Abstract

A complete first-principles thermodynamic model was developed and applied to hexagonal close-packed structure ε-Fe 3 N. The electronic structure was calculated using density functional theory and the quasiharmornic phonon approximation to determine macroscopic thermodynamic properties at finite temperatures was generalized in terms of the partition function for any lattice of interest.Specially, thermal expansion of the hexagonal close-packed ε phase with two independent lattice parameters was studied by means of the present model and first-principles phonon calculations. The present predictions of thermal expansion of ε-Fe 3 N are in good agreement with experimental data.

Influence of elevated temperature and reduced pressure on the degradation of iron nitride compound layer formed by plasma nitriding in AISI D2 tool steels

“…From this line shift, the relative reduction of the lattice parameters a and c was calculated and corrected for the thermal expansion (Figure 4). The thermal expansion was corrected according to Reference 35 in order to be able to correlate the reduction of the unit cell volume of ε‐Fe 3 N y directly with the out‐diffusion of nitrogen. As shown by Liapina et al 20 the lattice parameters and the volume of the unit cell of ε‐Fe 3 N y depend on the nitrogen concentration ( y ) like: …”

“…(A) Relative changes of the lattice parameters a (filled dots) and c (open triangles) of ε‐Fe 3 N y obtained from the HTXRD measurements and corrected by using the linear thermal expansion of the unit cell taken from Reference 35. (B) The corresponding nitrogen content in ε‐Fe 3 N y was estimated from the volume of the unit cell (Equation (2))…”

Stability of eutectic carbide in Fe-Cr-Mo-W-V-C alloy by first-principles calculation

“…e l s e v i e r . c o m / l o c a t e / m a t d e s to study the stability and electronic structure of γ-Fe 23 C 6 , and showed that the γ-(Fe, M) 23 C 6 phase is slightly more stable than cementite θ-Fe 3 C. Moreover, there have been many works on the stability of alloy carbides and interfacial property between the carbide and matrix in steels [12][13][14][15]. In our previous work, a novel steel for cold work roll was designed and optimized by CALPHAD.…”

Synthesis, Structure, and Magnetic Properties of B‐Doped Fe3N@C Magnetic Nanomaterial as Catalyst for the Hydrogen Evolution Reaction

“…Recently, iron nitride materials have become research hotspots due to their excellent properties, such as high melting point, high stability, wear resistance, high tensile strength, and electrical conductivity . Accordingly, iron nitride materials have broad applications in many fields, such as superconducting materials, superhard coating materials, high thermal conductivity materials, catalysis, and so on . Most studies of iron nitride materials are focused on magnetic and catalytic fields at present .…”