INFLUENCE OF HELIUM ON MICROSTRUCTURAL EVOLUTION IN AN ION-IRRADIATED LOW-SWELLING STAINLESS-STEEL

The evolution of damage in a tow-swelling stainless steel under ion irradiation is examined. The influence of the presence of helium and its mode of injection upon dislocation evolution, phase instability, and swelling are investigated. Comparison of the response of the low-swelling alloy with that of a high-swelling alloy leads to some conclusions on the origin of the observed swelling resistance. The dislocation loop evolution can be modified by the presence of helium during the nucteation stage. The influence of helium on phase instability arises from its modification of the loop substructure at which solute segregation occurs. Phase instability is not a sufficient condition for void formation in the swelling resistant alloy. Titanium getters soluble gases which aid void nucleation, while silicon may influence swelling by a trapping mechanism. © 1979.