Based on finite element simulation of nanoindentation, that is, forward analysis, the effect of AISI-304 SS substrate on Ti and Cr thin films was studied. Ti/AISI-304 SS is a soft film/hard substrate system, while Cr/AISI-304 SS is a hard film/soft substrate system. According to the practical working condition, in forward analysis the power law constitution was adopted with the elasto-plastic parameters of thin films and substrate given. Through forward analysis, it can be found that the substrate has a more apparent influence on elastic modulus of thin films than on hardness, and that the 10% rule is not applicable when it comes to elastic modulus. The Von Mises equivalent plastic strain distributions of Ti/AISI-304 SS and Cr/AISI-304 SS indicate that the soft film/hard substrate system has a sinking-in phenomenon and the hard film/soft substrate system has a piling-up phenomenon. Through the Von Mises equivalent stress distributions of Ti/AISI-304 SS and Cr/AISI-304 SS, their failure positions and modes were determined. Radial crack occurs on the surface of Ti film while circumferential crack occurs on the Cr film surface.

nanoindentation; finite element simulation; forward analysis; metal thin films; substrate

Taiyuan University of Technology