Thermodynamic studies of oxygen behavior in tantalum-based alloys |
| |
Affiliation: | 1. Institute for Materials Science, University of Stuttgart, Stuttgart 70569, Germany;2. Institute of Solid State and Materials Physics, Dresden University of Technology, Dresden 01062, Germany;1. National Institute of Advanced Industrial Science and Technology (AIST), AIST Central-5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan;2. Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan |
| |
Abstract: | An experimental study of equilibrium thermodynamic properties of oxygen in pure tantalum and tantalum alloyed with V, Nb or Mo was made by EMF measurements on solid electrolytic cells over the temperature range of 873–1373 K (600–1100°C). The solubility of oxygen in pure tantalum in equilibrium with Ta2O5 was determined to be Cs = 12.4exp[−(16 kJ/mol)/(RT)] over the experimental temperature range. It was concluded that oxygen obeys Henry's law for concentrations up to the terminal solubility in tantalum for the temperature range 873–1373 K (600–1100°C). The oxygen activity coefficient increased with Mo content in TaMo alloys and decreased with V content in TaV alloys. The equilibrium results showed virtually no change in thermodynamic behavior of the oxygen solution by adding Nb to TaO alloys. The positive deviation of the oxygen activity coefficient in TaMo alloys is evidence of a repulsive interaction between molybdenum and oxygen atoms. The interaction energy was calculated assuming that the interaction extends to third nearest neighbors. It may, in fact, extend to fourth or higher neighboring shells of atoms. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|