ENHANCED MECHANICAL AND MAGNETIC-PROPERTIES OF GRANULAR METAL THIN-FILMS

The mechanical properties of Ag-Al2O3 and Ni-Al2O3 granular metal films, as well as the magnetic behavior of the nickel-based films, is presented. Enhancements in the mechanical properties of these materials, as measured by low load indentation techniques, were observed for a metal volume fraction p of about 0.55. This volume fraction corresponded to the percolation threshold p(c) as determined from the magnetic measurements. A peak in the compliance as a function of p was observed, similar to elastic anomalies reported for small bilayer period superlattices. A discontinuity in the rate of change of hardness as a function of p was also observed, and believed to result from a change in deformation mechanism at p(c).