TEM Investigation on the Dislocation Loops in Zirconium Alloy by Neutron and Kr+ Ion Irradiation Tests

Neutron irradiation (E >= 1 MeV) and 400 keV Kr+ ion irradiation tests were carried out and compared to study the formation and growth mechanism of dislocation loops in zirconium alloys. The results show that, as the irradiation reached 1.9 x 10(25) n/m(2) and 1.0 x 10(20) Kr+/m(2), a large number of <a>-type dislocation loops and a small amount of large-sized <c>-type dislocations hundreds of nanometers or even micrometers in size are observed in both samples. EDS results confirmed that the concentrations of Nb and Fe in the <c>-type dislocation loops are higher than that in the matrix. With the increases of the dislocation loop size, part of the loop structure will decompose into the twisted, small-sized dislocation lines. Between two of the small-sized dislocation lines, a cubic structure was observed.