Effect of alloying additions on oxygen solubility in tantalum

The solubility of the oxygen in the tantalum and the effect the addition of titanium, zirconium, molybdenum and tungsten has on the solubility, have been investigated using the microstructural analysis techniques and by measuring the microhardness. In order to introduce the measured out quantities of oxygen, the samples have been anodeoxidized, following which an oxide film of a preset thickness has been formed. Subsequently, the samples have been annealed in the vacuum during 5 minutes at 1750 deg C. The research has shown, that with the cooling of the tantalum from 1750 deg C down to the room temperature, the oxide phase appears when the oxygen concentration in the pure metal reaches o.15%. Alloying of the tantalum with titanium and zirconium causes the appearance of the oxide phase with the 0.02-0.07% concentration of oxygen depending on the alloying admixture content. However, alloying with tungsten and molybdenum has almost no influence on the oxygen solubility