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Many methods are used to harden tantalum (solid-solution hardening, plastic deformation, grain ordering, dispersion hardening, and introduction of hardening dispersion phases in the form of particles, filaments, whiskers, fibers, etc.). The influence of conditions of glow-discharge nitriding of tantalum and the alloy Ta-10% W on the microhardness and phase composition of the diffusion layer is discussed.N itriding is a comparatively new method of hardening tantalum and its alloys [ 1, 2]. The use of a glow discharge makes it possible to substantially extend the technological capabilities of nitriding. Ion-beam nitriding has a number of advantages over ordinary gas nitriding [3]. Its main advantages are a high saturation rate and a possibility of controlling the structure and phase composition of the layers obtained so as to ensure that the parts treated have the necessary ensemble of service characteristics. The published data on ion-beam nitriding of tantalum and its alloys are limited. Accordingly, the sequence of phase formation and the effect of substitutional alloying elements on nitrogen diffusion in tantalum remain open questions.We studied high-purity TVCh tantalum and the commercial tantalum-tungsten alloy TV-10 (Ta-10% W). Ion-beam nitriding was carried out an experimental setup in purified nitrogen in the temperature range 700-1000°C and a saturatingmedium pressure of 0.4-20 GPa for 0.5-5 h.The structure and phase composition of the nitrided alloys were studied by metallographic, electron-microscopic, massspectrometric, and microdurometric methods.The microstructure of the nitrided layers was studied under a NEOPHOT 21 metallographic microscope. Thin foils cur from various parts of a layer were examined in a JEM-100B electron microscope. The nitrogen distribution in the surface layer was evaluated by secondary-ion-mass spectrometry on an a-DIDA instrument. The phase composition of the diffused layers was determined by layer-by-layer x-ray structural analysis. The x-ray photographs were taken in copper and iron characteristic Kc~ radiation on a DRON 2 diffractometer with monochromatization by the ionization method. On the basis of the x-ray structural data we also determined the thickness of the nitride zone. The microhardness of the nitrided alloys was measured on a PMT-3 instrument under a load of 0.5 N.The nitride zone of the nitrided layer, as a rule, is very small and after nitriding even at high nitrogen pressures in the working chamber of the apparatus is not more than 3-5 ~m thick and so is not always detected metallographically. The nitride zone is visible in microsections of samples nitrided for a long time only after saturation at nitrogen pressures higher than 15 GPa.The microstructure of the base of the alloys (core), corresponding to the annealed state, remains virtually unchanged after nitriding in the given range of temperatures and pressures. Because it is so thin the inner nitride layer is not revealed after treatment at the indicated nitrogen pressures.The phases formed in the nitride...

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The effect of low-temperature liquid borating on the structure and hardness of steel 38KhN3МFА is studied. It is found that in the borating process at temperature 600...660 °C and duration 8...32 hours boride coating with thickness of 6...19 μm with surface hardness of 1900...2000 HV is formed on the steel surface. The optimal borating regimes are determined, in which hardened layer with solid core is formed. The presence of two boride phases FeB and Fe2B in the boride layer is established by metallographic, X-ray and electron microscopic analyzes.

The effect of low-temperature liquid borating on the structure and properties of Ni-resist cast iron is studied. Metallographic studies and optimization of low-temperature liquid borating modes are performed. It is found that after low-temperature liquid borating increases the corrosion resistance of Ni-resist in the reservoir fluid simulator is more than 50 times, and in the washing liquid simulator — more than 100 times compared to the initial state. The developed technology of low-temperature liquid borating provides increase in the water-resistance of Ni-resist cast iron.