TDPAC measurements of untreated and control samples revealed a loss of anisotropy which was attributed mainly to the association of probe atoms with defects that were produced by (n,γ) reactions with isotopes of Ni and were subjected to magnetic and quadrupole interactions of comparable strength. The evolution of the Ni matrix was studied as a function of the isochronal annealing temperature in He-free α-irradiated or homogeneously He-implanted samples. No defect-associated Larmor precession frequency and/or quadrupole frequency was detected in these uncorrelated damage studies. A comparison of the recovery stages of α-irradiated and He-implanted samples indicated a binding of He-associated defects by Hf impurities. The segregation of Hf was detected in He-free α-irradiated samples upon annealing at 973K. No such effect was detected in He-implanted samples after isochronal annealing at up to 1273K.

Hf Impurity and Defect Interactions in Helium-Implanted NiHf. R.Govindaraj, K.P.Gopinathan, B.Viswanathan: Nuclear Instruments and Methods in Physics Research B, 2001, 179[2], 200-8