In-situ field-ion microscope study of the recovery behavior of heavy metal ion-irradiated tungsten, tungsten (rhenium) alloys and molybdenum. [30 keV W/sup +/ and Mo/sup +/]

Three field ion microscope (FIM) experiments were carried out to study the annealing behavior of heavy ion irradiated tungsten, tungsten (rhenium) alloys and molybdenum. The first experiment dealt with the stage I long-range migration of tungsten self interstitial atoms (SIAs) in high purity tungsten of resistivity ratio, R = 24,000 (R = rho/sub 300//rho/sub 4/./sub 2/, where rho/sub 300/ and rho/sub 4/./sub 2/ are the room temperature and 0/sup 0/C resistivities). The FIM specimens were irradiated in situ at 18 K with 30 keV W/sup +/ ions to an average dose of 5 x 10/sup 12/ ions cm/sup -2/ and subsequently examined by the pulsed-field evaporation technique. The second experiment dealt with the phenomenon of impurity atom trapping of SIAs during long-range migration. It was shown that rhenium atoms in a tungsten matrix tend to capture tungsten SIAs and remain bound up to temperatures as high as 390 K. The final experiment was concerned with the low temperature annealing kinetics of irradiated molybdenum. High purity molybdenum of resistivity ratio R = 5700 was irradiated at 10 K with 30 keV Mo/sup +/ ions to a dose of approximately 5 x 10/sup 12/ ions cm/sup -2/. The results indicated that the electric field has only a minimal effect on the SIA annealing kinetics. This tends to strengthen the contention that the molybdenum SIA becomes mobile at 32 K