First-Principles Investigation of Interfacial Bonding, Stability, and Electronic Properties at the...

Area of Science:

• Materials Science
• Computational Materials Science
• Solid State Physics

Background:

• Iron-based composites with MAX phases like Ti3SiC2 are crucial for advanced coatings.
• Understanding interfacial properties is key to optimizing composite performance.
• Heterogeneous nucleation of iron grains on Ti3SiC2 influences material microstructure and properties.

Purpose of the Study:

• To elucidate interfacial bonding mechanisms between Fe(111) and Ti3SiC2(0001).
• To investigate the heterogeneous nucleation behavior of Ti3SiC2 in iron-based composites.
• To determine the most thermodynamically stable Fe/Ti3SiC2 interface configuration.

Main Methods:

• Systematic first-principles density functional theory (DFT) calculations.
• Utilized Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) functional.
• Employed ultrasoft pseudopotentials (USPPs) within the CASTEP code for 18 interface models.

Main Results:

• The C(TiC)-terminated interface with HCP stacking showed the highest work of adhesion (9.25 J·m⁻²) and lowest interfacial energy.
• Strong covalent bonding between Fe 3d and C 2p orbitals drives interfacial stability, confirmed by charge density analysis.
• The identified interface's adhesion surpasses that of the Fe/Fe melt interface, indicating Ti3SiC2's efficacy as a nucleation substrate.

Conclusions:

• Ti3SiC2 particles are potent heterogeneous nucleation substrates for iron grains.
• The Fe/Ti3SiC2 interface exhibits robust cohesion due to strong covalent bonding.
• Findings provide an atomistic basis for enhanced nucleation and cohesion in Fe/Ti3SiC2 composites, guiding future material design.