Effect of Irradiation on Carbide Evolution in a Pure Fe-2¼Cr-1Mo Ferritic Alloy

Ion irradiation was observed to accelerate the kinetics of the carbide evolution in a “pure” Fe-2¼Cr-1Mo steel. The type and structure of the phases were unchanged by irradiation compared to thermal annealing. The transformation kinetics of Fe₃C to M₇C₃ and the independent nucleation of Mo₂C were both enhanced by the ion irradiation. The observed irradiation enhancement of the kinetics however did not follow a predicted trend based on a simple radiation enhanced diffusion model. There is no obvious explanation for this discrepancy except that mechanisms in addition to enhanced diffusion influence the complex transformation process.