Investigations on fatigue behavior and surface damage of Cu film by nano impact and molecular dynamics simulation

摘要

The fracture resistance of nanoscale MEMS films under high frequency impact seriously influences its service life. Nano impact test is a reliable technique to evaluate the fatigue fracture resistance of films by simulating the dynamic cyclic loading conditions. In this paper, a kind of Cu film was prepared by magnetron sputtering. The effects of loading parameters and indenter size on the fatigue damage behavior were studied for the Cu films during by nano impact test technique. The dislocation propagation and crack initiation during the nano impact process were also analyzed by molecular dynamics simulation. The results show that: Nano impact failure of Cu film can be divided into three stages and the main failure forms are cracks and delamination. The increase of the indenter radius leads to the increase of fatigue indentation size. The deformation range and damage accumulation degree of thin film material also increased correspondingly. With the increase of nano impact loading rate, the film material suffered more momentum from the indenter. The fatigue damage energy accumulation accelerates the damage.