CHARACTERIZATION OF Ni-RICH INTERMETALLIC COMPOUND Ni3Al FILMS WITH SLOW POSITRON BEAM
Abstract
Ni-rich intermetallic compound Ni3Al films were deposited using the dual-target magnetron co-sputtering method. The grain-boundary and grain-size characteristics of the as-deposited and post-annealed Ni3Al films were investigated using a slow positron beam. The results demonstrate a distinct change of S-parameter and positron effective diffusion length Leff values as samples were annealed at different ambient atmospheres and temperatures. It shows that the positron trapping center is mainly associated with intergranular vacancies, and changes to either the vacancy cluster size or the grain size have been invoked to explain the changes of the values of the S-parameter and Leff. Ni-rich oxygen-Ni3Al films were also studied. All films were identified using X-ray diffraction and the results confirm the conclusion obtained by the slow positron beam.
