The Paton Welding Journal, 2016, #5-6, 134-136 pages
Application of additive technologies for growing large profiled single crystals of tungsten and molybdenum
V.A. Shapovalov, V.V. Yakusha, A.N. Gnizdylo And Yu.A. Nikitenko
E.O. Paton Electric Welding Institute, NASU
11 Kazimir Malevich Str., 03680, Kiev, Ukraine. E-mail: email@example.com
The paper considers application of additive welding technologies with regard to growing the super large single crystals of refractory metals. Main methods of tungsten and molybdenum single crystals production from liquid phase were analyzed. The perspectives of plasma-induction technology for growing the large plane single crystals of tungsten and molybdenum are shown. A process scheme of additive growth of the plane single crystals of refractory metals using plasma-induction method is described. It is determined that the developed method provides for the possibility of flexible regulation of thermal field of single crystal being grown. Application of local molten zone, formed by low power plasma arc with the parameters typical for welding processes, allows growing the tungsten large single crystals of 210?x180x20 mm size. The crystals are formed under conditions of heating with inductor high-frequency field to the temperature typical for hot deformation range. Given are the results of investigation of structural perfection of the growing crystals which verify the fact that the conditions of single crystals formation in plasma-induction zone melting provide for higher quality of single-crystalline structure than the methods, in which additional heating (electron beam and plasma-arc) is not used. It is determined that the plasma-induction process is characterized by formation of the regular dislocation structures, for which dislocation coalescence in low-angel boundaries are typical. 9 Ref., 7 Figures.
additive welding technologies, plasma-arc zone melting, tungsten and molybdenum single crystals, dislocation substructure
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