Radiation-induced segregation behavior in random and ordered face-centered cubic materials

Radiation-induced segregation has been studied in random solid solution alloys Ni-10%Al and Ni-6%Si, and in the ordered (L1₂ structure) intermetallics Ni₃Si and Ni₃Al. These materials were irradiated with 2 MeV He⁺ ions at a temperature between 0.45 and 0.557T_m and at an ion dose rate of approximately 1 × 10^-4 dpa per second. Subsequent Auger Electron Spectroscopy analysis showed that silicon segregated to the surface in the Ni-6% Si and Ni₃Si alloys, and aluminum segregated away from the near surface region in the Ni-10% Al alloy. The Ni₃Al samples exhibited no detectable segregation with respect to depth from the sample surface. The mechanisms that may give rise to this resistance to radiation induced segregation will be examined in terms of the mobility of the alloying constituents, ordering energies and atomic sizes.