The physical grounds and an experimental study of the efficiency of applying the zone recrystallization method in an electric field for zirconium refining from metal and gas-forming impurities are presented. The changes in the elemental composition, microhardness, and structure of the obtained ingots was investigated. It is shown that the application of the method can significantly reduce the content of interstitial impurities. Zirconium samples with a purity of 99.91 wt.% were obtained.

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The work studied the possibility of obtaining of the high-purity samples of zirconium and hafnium by the method of zone recrystallization of round rods with electron-beam heating in a vacuum of 1∙10-4 Pa. Some meltings were carried out in a constant electric field with the variability of its connection. It is shown that the simultaneous passage of several refining processes (evaporation of highly volatile metallic impurities, zone recrystallization with directional displacement of impurities to the end of the sample, electrotransport) made it possible to efficient refining of zirconium both from metallic impurities and from interstitial impurities. The best degree of purification was achieved when zone melting carrying out in an electric field directed opposite to the zone movement. In this case, the displacement of interstitial impurity ions coincided with the direction of movement of the liquid zone. Samples of zirconium with a purity of 99.89 wt. % were obtained (the concentration of aluminum was reduced by 5, iron - 11, copper - 45, chromium - 75, silicon - 10, titanium - 2.5, oxygen - 3.3, nitrogen - 3, carbon - 2 times). The hafnium samples refined by the zone recrystallization method were characterized by a purity of 99.85 wt. %. The concentrations of both all metal impurities and interstitial impurities were significantly reduced (concentration in wt% oxygen was 0.011, carbon - 0.0018, nitrogen - 5∙10-5). A study of gas evolution from samples of iodide hafnium and refined hafnium was carried out. It was found that the maximum gas release peak fell on the temperature range of 500 ... 550 °C. The use of an integrated approach, including high-temperature heating, stages of zone melting at different rates, and thermal cycling in the range of the polymorphic transformation temperature, made it possible to obtain single-crystal hafnium samples. According to X-ray diffraction data, the parameters of the hafnium crystal lattice were determined: а = (0.31950 ± 5·10-5) nm and с = (0.50542 ± 5·10-5) nm (at 298 K), which corresponds to the density ρ = 13.263 g/cm3 and axial ratio с/a = 1.5819.

The physical substantiation of titanium refining by crucibleless electron beam zone melting (ZM) method in vacuum was presented. Calculations of the equilibrium, limiting and effective distribution coefficients for impurity elements in the base metal were carried out. The refining of titanium was studied experimentally, and samples with a purity of 99.92 wt.% were received. The total content of impurities was reduced by a factor of 1.5 (from 0.12 to 0.08 wt.%). The concentration of interstitial impurities was significantly reduced (oxygen – by 1.3; carbon – by 2; nitrogen – by 2.5 times). The structure and microhardness were investigated.

The physical substantiation and an experimental study results of the application of zone recrystallization method in an electric field for the refining of titanium are presented. The elemental composition, microstructure and microhardness of the samples have been investigated. It is shown that refining process made it possible to significantly reduce the content of both metallic and gas-forming impurities. The oxygen concentration was reduced by 2.2 (from 0.033 to 0.015 wt.%), carbon – by 3.3 (from 0.01 to 0.003 wt.%), nitrogen – by 22 times (from 0.009 to 0.0004 wt.%). The purity of the obtained samples was characterized by a value of 99.95 wt.% by titanium content. The total amount of impurities had been reduced by a factor of 2.4 (from 0.12 to 0.05 wt.%).