Origin and influence of pre-existing segregation on radiation-induced segragation in austenitic stainless steels

摘要

The pre-existing segregation at grain boundaries in two austenitic stainless steels has been investigated by atom probe field ion microscopy and analyticla electron microscopy.In addition,the effect of radiation-induced segregation on the near-grain-boundary composition has been studied by analytical electron microscopy.Pre-existing enrichment of Cr.Mo,B,C and P and depletion of Fe an Ni near grain boundaries has bene observed.Significant affinity between Mo and N in both alloys is indicated by the detection of MoN~2+ molecular ions during field evaporatio.The pre-existing segregation is modified by radiation-induced segregation resulting in Ni and Si enrichment near the boundary as well as depletion of chromium adjacent to the boundary resulting in a "W-shaped" Cr profile.