Investigation of the swelling behavior of nanoprecipitate strengthened martensite-austenite dual phase steel under helium irradiation

The development of a new generation of irradiation swelling-resistant materials is a crucial step in improving irradiation stability. In this study, helium ions were employed to irradiate the solid solution (without nano- precipitates) and aging (nanoprecipitates in martensite) martensite-austenite dual phase steels. The temperature was maintained at 500 degrees C with a fluence of 1.7 x 1017 ions center dot cm-2. The results show that the Cu-rich nano- precipitates within martensite coarsen after irradiation in the aged dual-phase steel. The pre-existing nano- precipitates effectively capture helium bubbles and inhibit their growth. The swelling rate of martensite is 0.095 %/dpa, only one-third of that in the solid solution state. During irradiation, high-density dislocations in austenite prevent the aggregation and growth of helium bubbles, resulting in a swelling rate of 0.082 %/dpa, which is superior to that of martensite in terms of irradiation resistance. The pre-existing nanoprecipitates in the aged steel and the high-density dislocations of austenite within the framework structure jointly enhance the resistance to irradiation damage, thereby exhibiting excellent anti-swelling properties.