RADIATION-INDUCED SEGREGATION BEHAVIOR IN RANDOM AND ORDERED FACE-CENTERED-CUBIC MATERIALS

Radiation-induced segregation has been studied in random solid solutio n alloys Ni-10%Al and Ni-6%Si, and in the ordered (L1(2) structure) in termetallics Ni3Si and Ni3Al. These materials were irradiated with 2 M eV He+ ions at a temperature between 0.45 and 0.55T(m) and at an ion d ose rate of approximately 1 x 10(-4) dpa per second. Subsequent Auger Electron Spectroscopy analysis showed that silicon segregated to the s urface in the Ni-6% Si and N3Si alloys, and aluminum segregated away f rom the near surface region in the Ni-10% Al alloy. The Ni3Al samples exhibited no detectable segregation with respect to depth from the sam ple surface. The mechanisms that may give rise to this resistance to r adiation induced segregation will be examined in terms of the mobility of the alloying constituents, ordering energies and atomic sizes.