MICROSTRUCTURE OF SINGLE AND DUAL-ION IRRADIATED FE-20NI-15CR AND TI-6A1-4V ALLOYS

An experimental austenltic alloy, Fe-20 wt. % Ni-15 wt. % Cr, and a commercial titanium alloy, Ti-64 (Ti-6 wt. % Al-4 wt. % V), have been dual-ion irradiated with heavy ions (Ni+ or V+) and 3He+, and also single-ion irradiated with heavy ions. For the Fe-Ni-Cr alloy, a dose dependence study at 700°C revealed that swelling decreased as the rate of helium injection was increased from 5:1 to 55:1 He:dpa (appm He:dpa); concomitantly, the nature of the cavities changed from void-like (underpressured) at 5:1 He:dpa to near equilibrium (or possibly overpressured) helium bubbles at 55:1 He:dpa. Furthermore, simultaneous injection of helum at 16:1 He:dpa did not cause a significant change in the peak swelling temperature. In the titanium alloy, both single and dual-ion irradiations caused profuse precipitation of β-phase (BCC) platelets in the α-phase (HCP) matrix at all irradiation temperatures (450-650°C). Cavities formed only at the highest irradiation temperature (660°C) during singleion irradiation, but formed at all irradiation temperatures (541-624°C) for dual-ion irradiation at 10:1 He:dpa. © 1979.