Proton Microprobe Investigation of the Migration of Molybdenum in Graphite at High Temperatures

The BNL proton microprobe has been used to study migration of molybdenum through reactor grade graphite for temperatures between 1800 and 3100°C. The proton microprobe, with a resolution between 25 and 150 micrometers, provides a unique tool for investigation of the lower temperature and shorter time heatings along with investigation of the microstructure of the system. With a high sensitivity, on the order of 1 ppm, particular attention was paid to the region governed by pore and grain boundary diffusion. The results obtained with the proton microprobe are compared with results obtained using wet chemical techniques.