TEMPERATURE-DEPENDENCE OF THE RADIATION-DAMAGE MICROSTRUCTURE IN V-4CR-4TI NEUTRON-IRRADIATED TO LOW-DOSE

Transmission electron microscopy (TEM) was performed on a V-4Cr-4Ti al loy irradiated to damage levels of 0.1-0.5 displacements per atom (dpa ) at 110-505 degrees C. A high density of small faulted dislocation lo ops were observed at irradiation temperatures below 275 degrees C. The se dislocation loops became unfaulted at temperatures above similar to 275 degrees C, and a high density of small Ti-rich defect clusters ly ing on {0 0 1} planes appeared along with the unfaulted loops at tempe ratures above 300 degrees C. Based on the TEM and tensile measurements , the dislocation barrier strengths of the faulted dislocation loops a nd {0 0 1} defect clusters are similar to 0.4-0.5 and 0.25, respective ly. This indicates that both types of defects can be easily sheared by dislocations during deformation. Cleared dislocation channels were ob served following tensile deformation in a specimen irradiated at 268 d egrees C. (C) 1998 Published by Elsevier Science B.V. All rights reser ved.