Collapse of Defect Cascades to Dislocation Loops During Self-Ion Irradiations of Fe, Ni and Cu at 30, 300 and 600 deg K

摘要

The formation of dislocation loops by self-ion irradiations of Fe, Ni and Cu has been studied in situ in the ANL High-Voltage Electron Microscope as functions of ion dose and irradiation temperature. At low doses (less than or equal to 10 sup 12 ions/cm sup 2 ) at room temperature individual cascades were observed to collapse to vacancy dislocation loops in Cu with high probability, in Ni with lower probability, and in Fe with zero probability. Cascade collapse was observed at low doses at 30 deg K in Cu and Ni, but at rates less than their respective rates at room temperature. A loop formation rate for Ni at 600 deg K is also reported. At higher doses (>10 sup 13 ions/cm sup 2 ) where overlap of cascades becomes significant, loops were first observed in Fe and with a supra-linear build-up with dose. Also at higher doses a decrease in loop production rate in Cu and Ni was observed due to loop coalescence. The materials and temperature dependence of cascade collapse probabilities are suggested to be related to thermal spike mechanisms during the cascade formation lifetime. (ERA citation 11:047920)