Helium implanted AlHf as studied by Ta-181 TDPAC

Time differential perturbed angular correlation (TDPAC) measurement on <(Al )under bar>Hf reference sample has shown that a fraction 0.88 of probe nucl ei are defect free and are occupying the substitutional sites in fee Al mat rix, and the remaining are associated with Hf solute clusters. Measurements on helium implanted sample indicate the binding of helium associated defec ts by Hf solute clusters. Isochronal annealing measurements indicate the di ssociation of the helium implantation induced defects from Hf solute cluste rs for annealing treatments beyond 650 K. On comparison of the present resu lts with that reported in <(Cu)under bar>Hf subjected to identical helium i mplantation, it is inferred that the Hf solute clusters in <(Al)under bar>H f bind less strongly the helium associated defects than in <(Cu)under bar>H f.