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Донецкий национальный технический университет, ул. Артема 58, 83000 ДонецкThe kinetics of hydrogen-induced direct phase transformation, i.e. decomposition process of Y 2 Fe 17 initial alloy at interaction with hydrogen on YH 2 hydride phase and a-Fe phase of iron, in Y 2 Fe 17 hard magnetic alloy has been studied. It has been established that, as the temperature increase from 610 to 750˚С, a direct phase transformation significantly accelerates. The activation energy of phase transformation process has been determined from kinetic data (163÷242 kJ/mol) that it is correspond to the values of activation energy of the iron atoms diffusion in R-T type alloys. It has been shown that the kinetics of hydrogen-induced direct phase transformation in Y 2 Fe 17 hard magnetic alloy is controlled by the Fe atoms diffusion to growing new a-Fe phase centers.

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Донецкий национальный технический университет, ул. Артема 58, 83000 Донецк, Украина The kinetics and features of nanocrystalline microstructure formation during direct and reverse hydrogen-induced phase transformations in Nd 2 Fe 14 B alloy has been studied. It has been established that a hydrogen-vacuum treatment carried out in accordance with the kinetic data of transformations in Nd 2 Fe 14 alloy leads to a formation of nanocrystalline homogeneous microstructure with average grains size ~0.3 μm. It is shown that carrying out direct and reverse transformations taking into account of kinetic features of transformations as temperature and transformation time allow to avoid abnormal growth processes a main hard magnetic Nd 2 Fe 14 B phase that is one of the main factors for permanent magnets obtaining with high coercivity without very complicated and expensive of alloying procedures.

In this study the breakdown voltage for Ti/4H-SiC type Schottky diode with six guard rings and JTE layer has been calculated by mean of numerical simulations. It is established that increase of the n-type 4H-SiC epitaxial layer from 14 up to 20 μm and addition of JTE layer lead to increase of breakdown voltage value on ∼900 V in contrast to the same diode without JTE. The above-mentioned diode’s structure gives the possibility for designing and production of diode with higher breakdown voltage value up to 3 kV.