Nikitenko Y. Producing of quick-hardened high-reactive and refractory alloys in induction and plasma-arc melting.

The thesis is devoted to the development of technologies of producing quick-hardened alloys using the method of dispersion during the induction melting in a sectional mould and spinning during plasma-arc melting in a water-cooled crucible. The thermo-physical, physical-chemical and materials science bases of the processes being investigated are considered. The thermal state of melting chambers of installations of IMSM and PAR was studied and main heat-loaded components were defined and quantitative characteristics of heat losses in separate components were given, the coefficients of remelting efficiency were determined. Using methods of mathematic modeling the laws of thermal interaction between the melt and drum-cooler in spinning were defined, which were confirmed experimentally. Technological parameters of producing quick-hardened pig ingots of alloys : D16, EP648, Ni-Ti, VT1-0, Nd-Fe-B, RSR of 15-50 m thickness, and strips :Ni-Si-B, Cu-P, Fe-Cr-Ni-B of 30-100 m were determined. On the example of amorphous alloy Ni-Si-B the nucleation of crystals and formation of crystalline structure in strip during annealing was studied. The effect of temperature on grain size, amount of amorphous and crystalline phase, main compounds, which are formed in annealing, were defined. The developed equipment and technologies allow giving recommendations for their application in producing high-reactive and refractory amorphous and microcrystalline alloys.