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Ion damage microstructures in a Fe-10Cr-6Mo-0. 5Nb ferritic steel

Conference ·
OSTI ID:5831734

An annealed-and-aged ferritic steel containing fine NbC precipitates and relatively coarse particles of Laves phase was bombarded with 4-MeV iron ions to 100 displacements per atom (dpa) at 400 to 600/sup 0/C. Much of the damage structure consisted of dislocation tangles that coarsened with increasing temperature. Cavity formation began at 450/sup 0/C, peaked at 500 to 550/sup 0/C and was absent at 600/sup 0/C. Maximum swelling was only 0.2%. The Laves particles exhibited recoil dissolution and restructuring. Bombardments with Fe + He + D or Fe + He beams at ratios of 10 atomic parts per million (appM) He/dpa and 45 appM D/dpa introduced high concentrations of very small bubbles and comparatively few larger, bias-driven cavities. The latter were initiated at bubble clusters on NbC particles. Maximum swelling of 0.75% occurred at 550/sup 0/C. Recoil dissolution of the Laves phase was retarded by the gases. Large critical cavity sizesand unbalanced dislocation and cavity sink strengths contribute to low swelling of this alloy.

Research Organization:
Oak Ridge National Lab., TN (USA)
DOE Contract Number:
AC05-84OR21400
OSTI ID:
5831734
Report Number(s):
CONF-860605-11; ON: DE86008500
Country of Publication:
United States
Language:
English