Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2506.05852

A Combined DFT and MD Study on Interface Stability in Ferrite-Cementite Systems

Pablo Canca·Chu-Chun Fu·Christophe J. Ortiz·Blanca Biel
View original source ↗Read source document ↗Export metadata ↓

Abstract

Understanding the atomic structure and energetic stability of ferrite-cementite interfaces is essential for optimizing the mechanical performance of steels, especially under extreme conditions such as those encountered in nuclear fusion environments. In this work, we combine Classical Molecular Dynamics (MD) and Density Functional Theory (DFT) to systematically investigate the stability of ferrite-cementite interfaces within the Bagaryatskii Orientation Relationship. Three interface orientations and several cementite terminations are considered to identify the most stable configurations. MD simulations reveal that the (010)||(11-2) and (001)||(1-10) orientations are energetically favourable for selected terminations, and these predictions are validated and refined by subsequent DFT calculations. A key result of our study is the destabilizing effect of interfacial carbon atoms, which increase the interface energy and decrease the Griffith energy, indicating a reduced resistance to fracture. This finding contrasts with earlier reports suggesting a stabilizing role for carbon. Our analysis of the electronic structure shows that Fe-C bonding at the interface perturbs the metallic environment of interfacial Fe atoms. This bonding response explains the observed variations in magnetic moment and helps rationalize the trends in interface energy. We also establish correlations between interface energy, magnetic perturbation, and a bond-based descriptor quantifying new and broken bonds. These insights provide a physically grounded, predictive framework for the design and optimization of ferrite-cementite interfaces in advanced steels.

Explore related subjects

cond-mat.mtrl-scicond-mat.mes-hall

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Pablo Canca, Chu-Chun Fu, Christophe J. Ortiz, Blanca Biel. 2025-06-06. A Combined DFT and MD Study on Interface Stability in Ferrite-Cementite Systems. https://doi.org/10.1016/j.actamat.2025.121157

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Incommensurate structural and magnetic modulations in potassium-rich cryptomelane, K$_x$Mn$_8$O$_{16}$ ($x\approx1.45$)

Cryptomelane is a hollandite-like material consisting of K$^+$ cations in an $α$-MnO$_2$ tunnel-like crystallographic motif. Cryptomelane with stoichiometry K$_x$Mn$_8$O$_{16}$ ($x\approx1.45$) has been synthesized and its magnetic properties investigated using variable-temperature magnetic susceptibility, heat capacity, and neutron powder diffraction. Three distinct transitions at $T_1=184$\,K, $T_2=54.5$\,K, and $T_3=24$\,K are observed. At $T_1$ there is a subtle tetragonal$\rightarrow$monoclinic transition associated with emergence of a set of non-magnetic superstructure peaks indexable to a $\vec{k}_\mathrm{struc}\approx0.74\vec{c^*}$ incommensurate modulation parallel to the $α$-MnO$_2$ tunnels. Our findings are consistent with a relation previously reported in titanate hollandites, that $x\approx2|\vec{k}_\mathrm{struc}|$. Magnetic Bragg peaks emerge below $T_2=54.5$\,K, and their positions indicate an incommensurate modulated magnetic structure. The model consistent with the data is a dual-$\vec{k}_\mathrm{mag}$ structure with a ferromagnetic $|\vec{k}_\mathrm{mag}|=0$ component and an incommensurate $\vec{k}_\mathrm{mag}\approx0.37\vec{c^*}$, with the latter most likely to be helical. The period of oscillation of the incommensurate magnetic component is in line with predictions based on a Heisenberg spin Hamiltonian [Mandal \textit{et al}. Phys. Rev. B 90, 104420 (2014)]. Below $T_3=24$\,K, there is a magnetic transition, which gives rise to a different set of magnetic Bragg peaks indicative of a highly complex magnetic structure.

cond-mat.mtrl-sci↗
arXiv2026

An anisotropic functional for two-dimensional material systems

Density function theory is the workhorse of modern electronic structure theory. However, its accuracy in practical calculations is limited by the choice of the exchange-correlation potential. In this respect, two-dimensional materials pose a special challenge, as all these materials and their heterostructures have a crucial similarity. The underlying atomic structures are strongly spatially inhomogeneous, implying that current exchange-correlation functionals, that in almost all cases are isotropic, are ill-prepared for an accurate description. We present an anisotropic screened-exchange potential, that remedies this problem and reproduces the band-gap of 2D materials as well as the piecewise linearity of the total energy with fractional occupation number.

cond-mat.mtrl-sci↗
arXiv2026

Thermally-driven reorientation of the Néel vector in altermagnetic MnTe

Altermagnets are novel magnetic systems that possess a spin-polarized electronic band structure without a net magnetic moment, making them promising for device applications. Hexagonal MnTe, a prototypical altermagnet, arguably exhibits the most properties consistent with theoretical predictions, including an anomalous Hall effect despite a vanishing net magnetization, and altermagnetinduced electronic band splitting. However, fundamental questions remain, including why some effects only appear significantly below the magnetic ordering temperature. Here, we resolve this discrepancy by revealing a reorientation of the Néel vector in single-crystalline MnTe. The Néel vector points 30° from the a-axis at low $T$, before aligning directly with the a-axis around $T\simeq 260$ K. We attribute this to single-ion anisotropy, which depends on temperature-dependent lattice parameters. We obtained these results using muon-spin spectroscopy, magnetization measurements, and X-ray diffraction; we show that the findings are consistent with neutron diffraction. Manipulating this effect, for example through strain, could unlock sensitive electronic detection schemes for external stimuli, paving the way for functional altermagnetic devices.

cond-mat.mtrl-sci↗