Effect of Ti/Mo and Cr/Mo metallic multilayer films on fretting fatigue resistance of Ti-6Al-4V alloy

Ti/Mo and Cr/Mo metallic multilayer films with different periodicities were synthesised on a Ti-6Al-4V alloy surface by ion beam enhanced magnetron sputtering deposition process. The structure, bonding strength, microhardness and ductility of the multilayer films were measured. The effects of Ti/Mo and Cr/Mo metallic multilayer films on wear and fretting fatigue (FF) resistance of Ti-6Al- 4V were studied. The results show that the wear resistance of Ti-6Al-4V alloy is improved by the Ti/Mo and Cr/Mo multilayer films which exhibit high density, fine grain, high bonding strength and obvious superhardness phenomenon. Ti/Mo multilayer films with a 200 nm periodicity exhibit strong adhesion, high hardness, good toughness and excellent fatigue resistance, which bring a 30% increase in FF life of Ti-6Al-4V alloy. However, Cr/Mo multilayer films have only a minor effect on the FF resistance of the Ti-6Al-4V alloy due to their high hardness and low ductility.