Influences of surface preparation on nanoindentation pop-in in single-crystal Mo

Influences of surface preparation on the pop-in behavior of single-crystal Mo were examined in nanoindentation experiments. The Mo surface was prepared by electropolishing and then damaged in a controlled way by polishing with 0.05 μm alumina. The damaged layer was systematically removed in steps by chemo-mechanical polishing with the pop-in behavior statistically characterized at each step. The observations show how the statistics of pop-in can be used as a sensitive indicator of the state of mechanical damage in very thin surface layers.