TEM study of irradiation induced copper precipitation in boron alloyed EUROFER97 steel

Specimens of the European reference 9Cr-WTaV steel EUROFER 97 alloyed with ∝ 0.1 wt.% 10B and 0.5 wt.% Cu were neutron irradiated up to 16 dpa at 300 and 400 C to study an interplay between helium generated by nuclear reaction on 10B and copper precipitates on microstructure and mechanical properties. Before irradiation 2-3 nm copper clusters often trapped on grain or lath boundaries were observed. It was shown that after irradiation copper segregates either in the bulk material by forming Cu-clusters which are in many cases attached to helium bubbles or it further precipitates at lath and grain boundaries. The size of both copper clusters and helium bubbles increases with radiation temperature. (orig.)