Effect of proton irradiation on the coarsening of precipitation hardened ferritic fe(al, ni)

Coarsening of beta'-(NiA1) precipitates in a ferritic Fe-8.3A1-3, Ni-0.1 Nb (at.%) alloy with and without proton irradiation was studied by transmission electron microscopy (TEM) and compared to recent coarsening theories. Solubility limits and diffusion coefficients of the solutes were obtained by combined measurements of particle sizes (from TEM) and solute concentrations (from resistivity measurements). Proton irradiation at a dose rate of 2 x 10(-6) dpa s-1 enhanced the solubility of A1 below 900 K to a temperature independent value of 6.7 at.%, while the diffusion coefficients below 860 K were increased to an almost temperature independent value of about 2 x 10(-20) m2 s-1. Vickers hardness was maximum for average precipitate sizes of about 5 nm and an anti-phase boundary energy of about 0.4 J m-2 was derived. Hardness of solution annealed as well as of over-aged specimens increased under irradiation mainly due to the formation of new small precipitates.