The electronic structure, mechanical and thermal properties of VC, α-V₂C, β-V₂C, V₄C₃, V₆C₅ and V₈C₇ are investigated systematically by the first principles calculation using density functional theory combined with the Debye quasi-harmonic approximation. Formation enthalpy is calculated and used to estimate the stability of the V–C binary compounds. The electronic structures and chemical bonding characteristics are analyzed by the band structures, density of states and Mulliken population analysis. The elastic constants of single crystal, hardness, bulk, shear, Young's modulus and Poisson's ratio of the polycrystalline crystal are obtained and compared with the experimental results. The anisotropic mechanical properties are discussed using the anisotropic index, three-dimensional surface contours and their planar projections on different planes of the bulk and Young's modulus. VC exhibits the largest mechanical modulus because of its strong chemical bonding and α-V₂C reveals the weakest elastic anisotropy. The specific heats at constant pressure and volume and the thermal expansion coefficients of the V–C binary compounds versus T from 0–1000 K are calculated and the largest and smallest thermal expansion coefficients are attributed to α-V₂C and V₄C₃, respectively.

The phase stability, electronic structure, and elastic and metallic properties of manganese nitrides (Mn₄N, Mn₂N_0.86, Mn₃N₂, and MnN) were extensively studied by first principles calculations.

The abrasive wear resistance of zirconia toughened alumina (ZTA) ceramic particle reinforced high chromium cast iron (HCCI) composites has been systematically investigated using a moving wedge type of apparatus. The results of three-body abrasive wear show that the wear resistance of the composites with honeycomb is three times higher than that of the high chromium cast iron. The wear resistance of the composites with a honeycomb structure is close to that of the layer structure and is higher than that of the HCCI because the honeycomb wall in the cell honeycomb structure is prominent and because the honeycomb core is depressed. The wear mechanisms of the composites are mainly microcutting and fatigue fractures. The honeycomb structure forms a “macrocosmic shadow protection effect” and a “microcosmic shadow protection effect” to protect each composite and to improve the wear resistance of the composites.

The interaction of point defects (interstitial atoms and vacancy) in both BCC Fe and FCC Fe lattices were investigated by first-principles calculations. The goals were to find the equilibrium separation of two interstitial atoms in the iron lattice and to establish the maximum trapping capacity of a mono-vacancy in the iron lattice. Based on our study, the equilibrium separation values of C–C, B–B and C–B were about 5.31 Å in the BCC Fe lattice. In the FCC Fe lattice, the equilibrium separation of C–C, B–B and C–B was about 6.42 Å. A mono-vacancy is shown to be capable of steady trapping as many as 3 atoms to form VX_n (X = C/B, n = 0, 1, 2, and 3) and VCB, VC₂B and VCB₂ complexes in the BCC Fe lattice. For the FCC Fe lattice, it is energetically favorable for a mono-vacancy to accommodate 2 C atoms, 3 B atoms, 2 C atoms and 1 B atoms, 1 C atoms and 2 B atoms, and 1 C atoms and 3 B atoms to form VC₂, VB₃, VC₂B, VCB₂ and VCB₃ clusters, respectively. However, when four interstitial atoms are in the same plane and occupy the nearest interstitial sites around the vacancy, they can also form VC₄, VB₄, VC₂B₂ and VCB₃ in the BCC Fe lattice and VB₄ and VC₂B₂ in the FCC Fe lattice. Moreover, we also found that the trapping ability of a vacancy is stronger in BCC Fe than in FCC Fe. These results are in good agreement with the available calculations and experiments results.

The equilibrium crystal structures, stability, elastic properties, hardness and electronic structures of Fe–P binary compounds (Fe₃P, Fe₂P, o-FeP-1, o-FeP-2, FeP₂, m-FeP₄-1, o-FeP₄, m-FeP₄-2) are investigated systematically by first principles calculations. The calculated formation enthalpy is used to estimate the stability of the Fe–P binary compounds. Fe₃P has the largest formation enthalpy at −44.950 kJ mol⁻¹ and o-FeP-2 has the smallest at −78.590 kJ mol⁻¹. The elastic constants are calculated by the stress–strain method and the Voigt–Reuss–Hill approximation is used to estimate the elastic moduli. The mechanical anisotropy of Fe_xP_y compounds are studied using the anisotropic indexes and by plotting the 3D surface contour of Young’s modulus. The electronic structures and chemical bonding characteristics of the Fe–P binary compounds are interpreted by the band structures and density of states. Finally, the sound velocity and Debye temperatures of the Fe–P binary compounds are discussed.