Article ID



Preparation of High Purity Niobium by Electron Beam Melting and External Gettering



Yong Hwan Kim
Ryosuke O.Suzuki
Katsutoshi Ono


Proc. Conf. Electron Beam Melting and Refining, State of the Art 1994, Barkish Materials Corp. NJ, USA, (1994) pp. 141-155.


Physical properties of niobium are deteriorated by interstitial impurities such as oxygen and nitrogen. The removal of these gaseous impurities were studied by electron beam (EB) melting and solid state external gettering with Ti, Y and Zr. The buttons and ingots were repeatedly remelted and refined by EB furnace (max.140kW). Subsequently, the external gettering for oxygen and nitrogen was carried out by wrapping samples with active metal foils and annealing in evacuated quartz ampoules over 1273K. The purity of refined niobium was characterized by its hardness, specific resistivity, internal friction and residual resistivity ratio (RRR=r273/r4.2). The results of these measurements were compared with conventional gas analysis. Niobium was purified to the RRR of 100 through EB melting and 700 through external gettering.