Elastic Recovery at Static Loading and Impact Indentations in MgF2

The extent of elastic recovery at spherical indentations in MgF₂ indented by static and impact loads was analyzed. The fraction of the indentation depth that was recovered decreased with increasing static load. Similar results were observed for impact loads. The kinetic energy losses increased with a velocity exponent of 2.61 despite substantial variations in the contributions of various loss mechanisms over the range of velocities for which measurements were made. Apparently, the losses are partitioned among the various loss mechanisms that derive their energy from the elastic field.