The precipitation of O, and secondary lattice defect formation during medium- and low-temperature 2-stage annealing, was investigated by means of transmission electron microscopy and selective etching. The experimental results showed that O precipitation during medium-temperature 2-stage annealing was significantly suppressed by high-temperature pre-annealing. On the other hand, high-temperature pre-annealing had little effect upon the precipitation behavior during low-temperature 2-stage annealing.

S.Ishikawa, M.Matsushita, J.Shimomura: Materials Science Forum, 1995, 196-201, 1823-8