Heavy-ion irradiations of Fe and Fe–Cr model alloys Part 2: Damage evolution in thin-foils at higher doses

Abstract

A study of heavy-ion damage in Fe and Fe–Cr alloys started in Part 1 1 was continued with an investigation of damage development in UHP Fe and Fe–8%Cr at higher doses up to 2 × 1019 ions m−2 (∼13 dpa). In thin-foil irradiations with 150 keV Fe+ ions at 300°C and room temperature (RT), more complex microstructures started to develop in thicker regions of the foils at doses greater than about 2 × 1018 ions m−2, apparently involving cooperative interaction, alignment and coalescence of smaller loops. First strings of loops all with the same ½⟨111⟩ Burgers vectors formed. In UHP Fe irradiated at 300°C the damage then developed into colonies of resolvable interstitial loops with ½⟨111⟩ Burgers vectors. By a dose of 2 × 1019 ions m−2, large (several hundred nanometre) finger-shaped loops with large shear components had developed by the growth and subsequent coalescence of smaller loops. Similar but finer-scale damage structures developed in UHP Fe irradiated at RT and in Fe–8%Cr irradiated at both RT and 300°C.