Mechanism of Y2O3 as heterogeneous nucleus of TiC in hypereutectic Fe-Cr-C-Ti-Y2O3 coating: First principle calculation and experiment research

Abstract

The lattice misfit between Y 2 O 3 and TiC low index faces was calculated by the Bramfitt two-dimensional lattice misfit theory in this work. The interface electronic structure, adhesive work and interfacial energy of Y 2 O 3 (111)/TiC(110) interfaces were calculated by the first principles method. The interfacial bonding characters were analyzed by the interface charge density, electron density difference and mulliken populations. The microstructure of the hypereutectic Fe-Cr-C-Ti-Y 2 O 3 coating was observed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The calculational results show that, the lattice misfit of Y 2 O 3 (111)/TiC(110) interface is 8.6%, which meets that Y 2 O 3 acts as 2 medium effective heterogeneous nucleus of TiC. Four interface models have been constructed according to the surficial termination situations and interfacial atomic stacking modes, in which O-TiC2 interface is most stable. Its interface adhesive workis the largest (6.07J/m 2 ) and its interfacial energy is the smallest (-1.22J/m 2 ). And its interfacial bonding is a mixture of polar covalent, metallic and electrovalent bonds, which proves that Y 2 O 3 and TiC can form a stable interface. The experimental results show that, Y 2 O 3 particle exists in the core of the flower-like TiC particle in the hypereutectic Fe-Cr-C-Ti-Y 2 O 3 coating and they are combined tightly, which proves that Y 2 O 3 can act as the heterogeneous nucleus of TiC.

WS2 Nanopowders as High-Temperature Lubricants: An Experimental and Theoretical Study

“…Figure b–d shows the charge density at 100, 200, and 300 °C, respectively. It can be seen obviously that the bonding between S in WS 2 and Fe is strong . The charge density at 100 °C is higher than those at 200 and 300 °C, and so it is inferred that the bonding between S and Fe is stronger at 100 °C, which is consistent with the results of bonding energy.…”

Structure and properties of YAlO3/NbC heterogeneous nucleation interface: First principles calculation and experimental research

“…In all calculations of YAlO3 and NbC, the cut-off energy [29] was set to 500 eV. K-points sampling grids, which plays a role of sampling in reduced brillouin zone, was acquired by Monkhorst-Pack method [21]. K-points for the bulk, surface and interface models were set as 8 x 8 x 8, 8 x 8 x 1 and 8 x 4 x 1.…”

“…Xu et al [20] investigated the influence of different modulation ratios on TiAlN/TiN and TiAlN/ZrN multilayer interface structures, which show that the results of the calculations are consistent with the experimental results and the defects in the non-equilibrium deposition process are attributed to the formation of the metastable coherent interface. Our previous research shows that Y2O3 can act as the heterogeneous nucleus of TiC and refine it, when Ti and Y2O3 are added to Fe-based alloy simultaneously [21]. However, the interface relationship between YAlO3 and NbC has not been researched or reported by the first principles calculation at present.…”

“…The interfacial energy is an important parameter to evaluate the interface stability. Generally, the smaller the interfacial energy is, the interface structure is more stable [21]. The interfacial energy can be calculated by the equation as follows [34]: (15) where YAlO3 and NbC are the surface energy of YAlO3(001) and NbC(100) models; Wad is the work of adhesion of YAlO3(001)/NbC(100) interface.…”

“…Due to the ability of simulating and analyzing the interface properties and relationships of various phases in materials, the first principles calculation based on density functional theory (DFT) has aroused extensive attention [19][20][21]. Z.J.…”