Microstructural evolution in Cu-Al25 alloy under 300 keV Cu+ ion irradiation

Dispersion strengthened (DS) Cu-Al25 alloy containing small Al2O3 particles (∝4 nm in diameter) was irradiated by 300 keV Cu+ ion to doses of 10 dpa and 30 dpa with a displacement rate of 3.7 x 10-2 dpa/s at room temperature, which simulates the effects of high energy primary knock-on atoms (PKA) produced by 14 MeV neutrons. Microstructural evolution was investigated by transmission electron microscopy (TEM). Selected area diffraction (SAD) was used to study the phase stability of alumina under irradiation. The defect cluster structure formed by irradiation was investigated by dynamic two-beam techniques. Small particles of Al2O3 were dissolved under ion irradiation with increasing fluences. A large number of small Frank vacancy and interstitial dislocation loops (∝5 nm in diameter) with different Burgers vectors of a/3 left angle 111 right angle are produced by ion irradiation. At the region adjacent to the irradiation surface the number of vacancy loops was greater than that of interstitial ones. This result is in good agreement with the computer simulation results. (orig.)