Gas bubbles evolution peculiarities in ferritic–martensitic and austenitic steels and alloys under helium-ion irradiation

Transmission electron microscopy has been used to investigate the gas bubble evolution in model alloys of the Fe–C system, ferritic–martensitic steels of 13Cr type, nickel and austenitic steels under 40-keV helium-ion irradiation up to a fluence of 5 × 1020 m−2 at the temperature of 920 K. It was shown that helium-ion irradiation at high temperature resulted in formation of bubbles with a greater size and a smaller density in Fe and ferritic–martensitic steels than those in nickel and austenitic steels. Large gaseous bubbles in ferritic component are uniformly distributed in grains body in Fe–C alloys as well as in ferritic–martensitic steels. The bubbles with a higher density and a smaller size than those in ferritic component are formed in martensitic grains of steels and Fe–C alloys with a high carbon content (NC>0.01 wt%), which leads to a small level of swelling of martensite in comparison with that of ferrite. In addition, the bubbles in martensitic grains have a tendency to ordered distribution.