Browsing by Author "Shvachko, Sergiy"
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Item Experimental and First-principle study of TmNiSb half-Heusler Alloy(Видавництво Львівської політехніки, 2017-12-23) Rykavets, Zlata; Ryzhak, Diana; Romaka, Lyubov; Shvachko, Sergiy; Romaka, Vitaliy; Lviv Polytechnic National University; Ivan Franko National University of LvivThe studied TmNiSb alloy crystallizes in the MgAgAs structure type (half-Heusler phases) and according to the results of DFT+U calculations revealed the presence of bandgap (Eg = 359 meV). Spin magnetic moment of Tm atoms equals 2.16 μB confirming its Tm3+ state. Calculated elastic properties as well as Vickers hardness of TmNiSb alloy was defined semi-empirically and equals 15.98 GPa. Experimentally determined microhardness is within the range of 2.90 – 4.06 GPa with the exception of TmNiSb phase.Item Methods of rolled copper wire properties improvement(Lviv Polytechnic Publishing House, 2015) Duriagina, Zoya; Dvorianyn, Khristyna; Shvachko, Sergiy; Pleshakov, Eduard; Tepla, Tetiana; Lviv Polytechnic National UniversityHot cracks of rolled copper are the most wide spread type of discards under continuous casting which are eliminated with difficulty. In industrial production of rolled copper wire at the plants of Ukraine the amount of oxygen in the obtained rods does not exceed the standard values. In this paper it is proposed to subject the melt to ultrasonic treatment to degassing process and the formation of homogeneous, dispersive sub dendrite structure of the rolled copper.