Computer Simulation Study of the Precipitate-Matrix Interface in an Fe-Cu System

An important mechanism in the embrittlement of steels and Fe-Cu alloys under irradiation and/or thermally aging is the formation of Cu-rich precipitates. The properties of such precipitates and their interactions with other defects of the ferritic matrix is of crucial importance for the understanding of the mechanical behavior of steels. Recent studies of Cu-precipitation in ferritic alloys demonstrated that during aging, Cu-precipitates grow coherently with the bcc-matrix up to a size of approx7 nm. Long time aging leads to bigger precipitates, which transforms to the 9R and then to the fcc structure. The existence of big Cu particles containing 10 exp 5 -10 exp 6 atoms with the otherwise unstable bcc structure is the effect of the precipitate-matrix interface (PMI). In our previous work we found that some specific properties of the precipitates and its interaction with point defects are related to the PMI. In this communication we summarize these results and include new ones that emphasize the importance of the precipitate-matrix interface.