Swelling and radiation-induced segregation in austentic alloys

To elucidate the relationship between radiation-induced segregation and swelling in austenitic stainless steels, a series of alloys were irradiated with 3.2 MeV protons to doses of 0.5 and 1.0 dpa at 400 °C. Three alloy series were irradiated, the first to examine the effect of bulk nickel in Fe-16-18Cr-xNi, the second to determine the effect of Mo and P in an Fe-16Cr-13Ni base alloy, and the third to examine the effect of oversized solute Zr addition to an Fe-18Cr-0.5Ni alloy. The addition of nickel in Fe-16-18Cr-xNi caused a significant decrease in swelling and increase in segregation. The addition of Mo+P to Fe-16Cr-13Ni eliminated swelling and reduced segregation. The addition of Zr to Fe-18Cr-9.5Ni decreased swelling and altered the segregation. Comparison of swelling with changes in lattice parameter and shear modulus caused by the segregation showed that swelling correlates well with the decreases in lattice parameter caused by radiation-induced segregation. Those alloys whose segregation decreased the lattice parameter the greatest showed the lowest swelling. These results are consistent with theoretical predictions made by Wolfer.