Phase instability and void formation in neutron-irradiated Fe-Cr-Mn-Ni alloys

Abstract

A series of Fe-13Cr-15Mn alloys with different nickel levels of 0-15% have been examined by transmission electron microscopy and X-ray microanalysis following irradiation to 17-25 dpa at 693-823 K. All specimens were found to have developed typical features of radiation damage at high temperature; voids, dislocations and second phases. Both void formation and radiation-induced phase instability were found to be strongly dependent on nickel content. The ferrite phase was observed to form at grain boundaries in alloys with zero or low nickel content. Sigma phase often formed at the boundary between the ferrite and austenite phases. With increasing nickel content, both ferrite and sigma phase formation were suppressed. The induced density change was also found to be sensitive to the nickel content. The phase instability and density change during irradiation was explained in terms of radiation-induced solute segregation and formation of lower swelling phases. © 1993, The Japan Institute of Metals. All rights reserved.