HE-3 BEHAVIOR IN SOME NICKEL-BASED AMORPHOUS-ALLOYS

Helium trapping and release are studied for the nickel-rich amorphous alloys Ni75.1Cr14.0P10.1C0.08, Ni63.5Zr36.5, and Ni87.7P12.3. Helium-3 is introduced into the samples by implantation at 150-keV energy. The depth distribution of the implanted helium is observed by neutron depth profiling employing the reaction He-3(n, p)H-3. Two implantation doses are used: 1 x 10(16) and 5 x 10(16) He-3/cm2. Both implantation doses were chosen to be low enough to avoid blistering or flaking of the surface of the samples. The helium release behavior of the samples is studied by taking depth profiles after each annealing stage. At the same time, electron diffraction is used on parallel samples to observe the microstructure of the samples as a function of annealing. The annealing sequence for each material is broken off when electron diffraction indicated the existence of relatively large crystals in a sample. Only a small fraction of the implanted helium is released in most cases, and a clear correlation between helium release and recrystallization can be found in only one case.