REDUCTION OF FREELY MIGRATING DEFECT CONCENTRATIONS BY CASCADE REMNANTS IN NI-SI ALLOYS

Interactions of cascade remnants with freely migrating defects in Ni-1 2.7% Si were investigated using in-situ Rutherford backscattering spec trometry during simultaneous irradiation with 1.5 MeV He and 400 keV N e ions at elevated temperatures. Radiation induced segregation of Si a toms toward the specimen surface caused gamma'-Ni3Si layers to grow on the surface during irradiation. The gamma'-Ni3Si growth rate during H e bombardment was strongly suppressed by simultaneous irradiation with Ne ions, even when the calculated defect production rate for the Ne i ons was only a few percent of that for the He ions. This result shows that the cascade remnants generated by the Ne ions act as additional r ecombination sites for freely migrating defects, reducing their steady state concentration. Despite a large difference in defect properties and in the kinetics of radiation induced segregation between the two a lloys, the effects of cascade remnants on freely migrating defects in Ni-12.7% Si are remarkably similar to those found previously in Cu-1% Au.