[en] A method of hydrostatic hot extrusion of thick-walled, capillary tubes of Cu-Cr-Zr and of dispersive strengthened copper Cu+3.5 vol.%. TiB₂, is presented. The quality-evaluation of the produced tubes is done. (author). 2 refs, 1 fig., 5 tabs

[en] Highlights: • Ti matrix composite reinforced with high aspect ratio TiB fibers is prepared “in situ” successfully by casting. • Orientation of TiB fibers and their strengthening factor as a function of the extrusion ratio are modeled. • The breaking of the TiB fibers may be responsible for the overestimated strengthening factor by the model used. • Extrusion is an effective process for fiber realignment to obtain high strength for this Ti composite. According to shear-lag model, fibers orientation in composites reinforced with short fibers has a significant effect on their strength which can be predict in term of strengthening factor (C₀) of fibers. In this work, titanium matrix composite reinforced with TiB fibers was fabricated with enhanced mechanical performances using in situ technologies plus extrusion process. The value of TiB fibers C₀ in the as-cast composite was calculated to be very low (0.125). Increase of the strengthening factor of TiB fibers by extrusion was modeled based on a deformation model. The value of C₀ is calculated to be 0.442, 0.713 and 0.812 with extrusion ratio 1.5, 2.0 2.5, respectively. Tensile tests showed that extrusion process increased strength of the composite significantly. But C₀ was overestimated by this model with high extrusion ratios. The overestimating may be attributed to the broke of TiB fibers during extrusion.

[en] The values given in the literature for the enthalpy of the formation of titanium diboride, as obtained experimentally and by theoretical estimation, range between -32 and -74.4 kcal/mol. In this paper the authors use the method of direct synthesis from elements in a Calvet calorimeter to determine the enthalpy of formation, ΔHsub(f)⁰, sub(298), of titanium diboride with the composition Tisub(1.000+-0.002)Bsub(2.056+-0.006)Csub(0.009)Nsub(0.003), which was found to be -76.78+-0.83 kcal/mol. They calculate that ΔHsub(f,298) (TiBsub(2.056)=-76.14+-0.85 kcal/mol. The procedure employed makes it possible to carry out the titanium diboride synthesis reaction with the calorimeter at room temperature

[en] The effect of true porosity and the mean size of pores on hardness of sintered materials based on titanium diboride is investigated. It is established that the Rockwell hardness dependence on porosity is exponential. At equal porosity of 3+-1% the hardness reduces linearly with the growth of the mean size of pores

[en] Chambersite (Mn₃B₇O₁₃Cl)–Ti composites were fabricated using spark plasma sintering. The microstructure and phase composition of the composites were investigated along with the effects of chambersite on the mechanical properties and friction properties of Ti. The results show that chambersite reacts with Ti during sintering to form TiB, Ti_xO_y, and MnCl₂. The mechanical properties of the composites were optimal for the composite with 5 vol% chambersite. Chambersite helps to improve the friction properties of Ti: with increasing amount of chambersite added, the wear rate of the composites decreases. (paper)

[en] Hardness of TiB₂ films is studied within load wide range including low-loads (nanoindentation). Ratio of final depth of indenter penetration (following load relieving) to penetration total depth is shown to constitute for films 0.67 and 0.63 respectively. 9 refs., 3 figs

[en] This paper reports on investigation of the simultaneous formation and sintering of TiB₂. The resulting material showed an equigranular structure with grain sizes > 1μm. Coherent grain boundaries were frequently observed. A new phase was found in grain boundaries, and the b-axis of the base was as much as 1 1/2 times longer than that of TiB₂

[en] The settlements and the grain refining action of TiB₂ particles in the melt of electrolytic low-titanium aluminum (ELTA) with Al-4B addition were investigated. The results show that numerous fine TiB₂ particles will be formed when Al-4B master alloy is added into the melt of ELTA at the Ti/B mass ratio of 5:1. Because of their fine sizes, though there are also TiB₂ particle settlements, there will still be more TiB₂ particles being suspended in the melt of the ELTA with Al-4B addition than in the melt of the pure Al with Al-5Ti-1B addition at a given Ti addition level. These fine TiB₂ particles, together with the titanium atoms left in the melt, will form more heterogeneous nucleation sites during solidification of the melt, improving the grain refining efficiency and the fading-resisting ability obviously. Comparing with the method of adding Al-5Ti-1B into pure Al, the present method has advantages in resulting in the formation of fine TiB₂ particles and preventing their settlements

[en] The oxidation and thermal-oxidative stability of titanium diboride are studied during its storage and heating in the air. It was established that during the first 24 hours titanium diboride actively adsorbs oxygen and moisture: the oxidation of TiB₂ (1) reaches 11.06·10⁻⁷, TiB₂ (2) –8.15 · 10⁻⁷, TiB₂ (3) – 31.5·10⁻⁷ kg O₂/m². Analytical dependencies were obtained for the calculation of oxidation. When heated in the air, titanium diboride nanocrystals are oxidized in the temperature range (623 – 673) ± 15 K, microcrystals at a temperature of 688 ± 5 K and higher. (paper)

[en] The Ti B₂ compound has high electrical conductivity, the metallic type of conduction and a complicated layer structure; this is typical of a number of high-temperature superconductors. The complicated structure of this compound is followed by triangular prisms of titanium with the boron atoms in the centre. The boron atoms, situated in the same plane, formed corrugated networks with hexagonal cells. In order to investigate the possibilities of the existence of high-temperature superconductivity in high-purity single crystals titanium diboride, investigations were carried out on specimens of this compound, with special reference given to their electrophysical properties