The effect of irradiation on the stability of precipitates in Zr-2.5 WT% Nb alloys

Abstract The effect of irradiation on the stability of precipitates in dilute Zr-Nb alloys has been studied using the HVEM. In a Zr-2.5 wt% Nb alloy, a dispersion of spherical, incoherent β-Nb precipitates in a recrystallised α-Zr matrix exhibited enhanced particle coarsening at 465° C during irradiation to 19 displacements per atom. The metastable, coherent ω phase in a Zr-12 wt% Nb alloy, however, progressively dissolved during irradiation at 350°C, but was simultaneously replaced by a considerably finer dispersion of the same phase, such that a net particle refinement occurred. These observations are discussed in terms of the present experimental and theoretical knowledge of the effects of irradiation on diffusion and precipitate dissolution.