THERMODYNAMICS OF THE INTERACTION OF NIOBIUM AND TANTALUM WITH OXYGEN AND NITROGEN AT TEMPERATURES NEAR THE MELTING POINT
Abstract
The concentration of N and O present in Nb and Ta in equilibrium with the pure gas has been determined as a function of pressure at each of 3 temperatures near the melting point, and in the liquid phase at the melting point. The solubility of N in Nb is directly proportional to the square root of the pressure (Sievert's Law) up to the solubility limit, where the saturated solution is in equilibrium with Nb2N. The solubility of N in Ta shows a negative deviation from Sievert's Law at N concentrations above 5 at-%; beyond the solubility limit saturated solution is converted to Ta2N. The Nb-O and Ta- O systems obey Sievert's Law up to the solidus point. The temperatures investigated were above the melting points of the metal oxides and no oxide scales were obtained. A curious solubility inversion was noted in the Ta-O system where the O concentration in equilibrium with a specified pressure of O is lower at 2850 than at 2960 deg C. It was shown that the concentration of H in equilibrium with metal at high temperature is very low.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1961
- Accession Number
- AD0262060
Entities
People
- J. P. Pemsler