This U.S.-Brazil Cooperative Research award supports cooperative research in high-temperature alloys between Dr. David Douglass of UCLA and Dr. Fernando Rizzo of the Catholic University (PUC) in Rio de Janeiro, Brazil. The purpose of this research is to conduct a study of the internal oxidation of various Nb alloys over the range of 1450-1900 C. Internal oxidation of Nb alloys occurs during heat treatment in "vacuum" over a wide range of oxygen pressure, and may occur also during high-temperature exposure of missile components at low oxygen pressures. A program involving the internal oxidation of Nb alloys, both binary and commercial alloys, is underway at UCLA under Professor Douglass. Some interesting preliminary results have been obtained to date over the temperature range of 1450-1950C and over a low oxygen-pressure range. This subject is an ideal one for collaborative research with Professor Rizzo. He will use the EDX/SEM method to measure these profiles. The data obtained will be analyzed in Brazil with his computer program to assess agreement between the experimental values and the calculated values. Douglass will fabricate ternary alloys of Nb-Mo-Hf and Nb-Mo-Zr which will be internally oxidized. The study of such alloys will enable control of internal oxidation to be shifted from the arrival and adsorption of oxygen on the surface to diffusion of oxygen in the substrate.
