Pressure and temperature effect on eguilzbrium content of impurities in niobium

Results of computer calculations modelling equilibrium states during niobium heating containing silicon, aluminium, carbon, iron titanium, oxygen, nitrogen impurities in the 2000-4000 K range at the pressure of 1.3X10-6-1.3X10-- 10 MPa (1X10-1-1X10-5 Hg) in the initial argon atmosphere, are presented. Calculations are performed modelling equilibrium states when refining niobium from Si, Al, C, Te, Ti, O, N impurities at the pressure of 1.3x10-5-1.3x10-10 MPa and the temperature of 2000-4000 K. Boiling (sublimation) temperatures of niobium, niobium losses, energy expenses for the process are determined. It is determined that the degree of purification from impurities increases with pressure reduction; at a given pressure the purification degree ceases in the series Al-Fe-Si-O-N-C. The analysis of experimental values of the purification degree from C, O, N during electron-beam remelting (EBR) is performed. In the case of single EBR average degrees of purification from C are 3.1; from N-4.5; from 0-11