111Cd Time Differential Perturbed Angular Correlation Study of Deformed Ni

Abstract

Using a time differential perturbed angular correlation (TDPAC) method with 111 In which decays to 111 Cd, the lattice defects induced by cold rolling in Ni metal at 77 K have been studied by the magnetic hyperfine fields observed at the 111 Cd probe nuclear sites. To investigate the dependence of annealing temperature, we have measured TDPAC spectra at 298 K during 1 hour isochronal annealing up to 1273 K in Ar + 7%H 2 gas atmosphere. After 1273 K annealing, only one component which shows ω L = 98.0 ± 0.5 Mrad/s corresponding to magnetic hyperfine field of 6.68 ± 0.02 T has been observed at 300 K. This frequency is interpreted as a hyperfine field at 111 Cd nucleus which occupies substitutionally the Ni lattice sites. We have also investigated the interaction between probe nucleus and lattice defects from the measurements of 111 Cd TDPAC spectra. After deformation, distinctive changes have not been observed. But after 473 K annealing, ω L = 40.60 ± 1.03 Mrad/s corresponding to magnetic hyperfine field of 2.77 ± 0.07 T was observed in addition to the component originating from the substitutional 111 Cd atoms. This frequency seems to be due to the component from the trivacancy trapping site. Because 111 In-V 3 site might transform immediately to 111 In - V 4 complex, and shows the cubic environment. This component disappeared after anneal ing above 873 K, and after 1273 K annealing the spectrum completely returned to the original substitutional 111 Cd spectrum before the cold rolling.