The conflicting roles of boron on the radiation response of precipitate-forming austenitic alloys at ∼400 °C

The behavior of void swelling at ∼400 °C of model f.c.c. alloy Fe–15Cr–16Ti–0.25Ti–0.05 C doped with boron was examined in the FFTF–MOTA. Boron additions modify the neutron-induced swelling of Fe–15Cr–16Ni–0.25Ti–0.05 C somewhat, but the changes appear to arise primarily from the influence of boron as a chemical species rather than as a source of helium. Boron additions initially depress swelling strongly, but the effect saturates by <100 appm. The reduction in swelling is thought to arise from boron’s influence on distribution and precipitation of carbon. As the boron level is raised to significantly larger levels swelling begins to increase, but at a slower rate per boron atom. This subsequent increase is thought to reflect the higher He/dpa ratio generated by the boron, overwhelming the helium produced by (n, α) reactions with nickel.