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[en] An indirect method (a hybrid one in comparison with known PVD and CVD methods) for creation of hard transition metal carbide coatings with good adhesion to the substrate is presented, involving vacuum annealing of thin carbide-forming metal layers on high carbon steel substrates. A phenomenological diffusion model for the system layer/substrate which well fits the experiment is also presented. (author). 5 refs, 13 figs
[en] For a system of spherical particles in a matrix, a relationship is derived between the equilibrium degree of particle contact and the ratio of the interfacial energies, i.e., the energy of the contact boundary between particles and of the particle--matrix interface. The degree of particle contact is expressed in terms of the contiguity and the average number of contacts per particle, both of which can be measured by counting on planar sections. Thus the relationship provides an alternative to the measurement of dihedral angle for the determination of the energy ratio. The method is applied to the systems TiC--Co, TaC--Co, and WC--Co and, in combination with wetting data, is used to estimate the surface and interfacial energies in these systems
[en] Using the double-shell model in a slab geometry, we calculate the surface phonons on the NbC (001) and TaC(001) surfaces for what we believe to be the first time. A small anomaly is found in the dispersion curve of the Rayleigh mode along the Gamma-bar--M-bar symmetry axis. Its magnitude is very small for NbC and is not inconsistent with recent observations. Moreover, the observed above-bulk mode is very well reproduced by our model. On the other hand, the agreement with the experiment is not so good for the optical modes. We propose possible changes of the shell-model parameters at the surface to resolve this disagreement
[en] Highlights: • TaC-LaB6 composites with 0.1–30 mol% LaB6 additions were fabricated by hot pressing. • Additions of LaB6 helped enhance densification of the TaC-based composites. • Compositions with 1–2 mol% LaB6 had relatively good mechanical properties. • Creep resistance was tested by sinter-forge at temperatures up to 1950 °C.