Porosity--strength relationship in a Cu-rich spherical alloy amalgam.

Porosity and strength of spherical Cu-rich alloy amalgams were analyzed in the under-graduate materials laboratory. The minimum value for porosity was obtained for 46% initial Hg content, whereas the maximum strengths were obtained for 42% initial Hg. This result did not coincide with the data previously obtained for the conventional spherical alloy amalgam, in which the maximum strength and the minimum porosity were strictly associated with the optimum initial Hg content. Although no critical value for porosity could be definitely demonstrated by this effort, this result may be an indirect indication for 4.5 vol% porosity as the critical value.