Heavy-ion cascade effects on radiation-induced segregation kinetics in Cu-1%Au alloys

Various dual ion irradiations were conducted to investigate the effect of h eavy-ion cascades on the fluxes of freely migrating defects which drive rad iation-induced segregation (RIS) in Cu-1at.%Au alloys. In situ Rutherford b ackscattering spectroscopy (RBS) was used to measure the RIS suppression ef fect of heavy-ion bombardment (with 300-keV Al+, 800-keV Cu+, and 1.2-MeV A g+) on 1.5-MeV He+-RIS of Au in the near-surface region of the alloy during concurrent He+ and heavy-ion irradiations at 400 degrees C. Results demons trated that the suppression of He+-RIS correlated well with the cascade vol ume produced by concurrent Al+, Cu+, and Ag+ irradiation per second and was independent of the weighted average primary recoil energy. Model calculati ons of the kinetics of RIS during dual beam irradiation were also performed and compared with the measurements. Information regarding the energetics o f freely migrating point defects and their relative production efficiencies was obtained from systematic fitting. Using the values previously reported for the energies of formation and migration for vacancies and interstitial s in Cu, the binding and migration energies of Au-interstitial and Au-vacan cy complexes in the alloy were found to be -0.14, 0.15, and 0.03 and 0.76 e V, respectively. The respective derived efficiencies of freely migrating de fect production by energetic He+, Al+, Cu+, and Ag+ ions were 0.25, 0.12, 0 .09, and 0.08. (C) 2000 Elsevier Science B.V. All rights reserved.