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

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 x 10(19) ions m(-2) (similar to 13 dpa). In thin-foil irradiations with 150 keV Fe-1 ions at 300 degrees C and room temperature (RT), more complex microstructures started to develop in thicker regions of the foils at doses greater than about 2 x 10(18) ions m(-2), apparently involving cooperative interaction, alignment and coalescence of smaller loops. First strings of loops all with the same 1/2 < 111 > Burgers vectors formed. In UHP Fe irradiated at 300 degrees C the damage then developed into colonies of resolvable interstitial loops with 1/2 < 111 > Burgers vectors. By a dose of 2 x 10(19) 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 degrees C.