Copper-rich precipitates could nucleate and grow in ferritic steels containing small amounts of Cu in solution and this affected mechanical properties. Growth kinetics, composition and structure of precipitates under irradiation were different from those under thermal aging, and also vary with type of radiation. This implied that the interaction between radiation defects, i.e. vacancies, self-interstitial atoms and their clusters, and precipitates was influential. It was studied here by atomic-scale computer simulation. The results were compared with those of elasticity theory based upon the size misfit of precipitates and defects, and the modulus difference between body-centered cubic Fe and body-centered cubic Cu. It was found that self-interstitial atom defects were repelled by precipitates at large distance but, like vacancies, attracted at small distance. Copper precipitates in Fe can, therefore, be sinks for both vacancy and interstitial defects and hence could act as recombination centers under irradiation conditions. A tentative explanation for the mixed Cu-Fe structure of precipitates observed in experiment and the absence of precipitate growth under neutron irradiation was given. More generally, agreement between the simulations and elasticity theory suggested that the results were not artefacts of the atomic model: both vacancy and interstitial defects in metals could bind to precipitates with weaker cohesion than the matrix.

Atomic-Scale Computer Simulation Study of the Interaction of Cu-Rich Precipitates with Irradiation-Produced Defects in Alpha-Fe. A.C.Arokiam, A.V.Barashev, D.J.Bacon, Y.N.Osetsky: Philosophical Magazine, 2007, 87[6], 925-43