Mechanical behavior of nanotwinned metallic alloy thin films

Abstract

For the last decade, nanotwinned metals attracted intense research interest due to enhanced mechanical, electrical and functional properties accompanied with the unique microstructure. Focus of this research is the mechanical characterization of nanotwinned nickel-molybdenum-tungsten thin films deposited via magnetron direct current sputtering. By modifying of the chemical composition and the deposition rate, change in the fraction of twinned grain is observed: films with additional Mo content and/or films that were deposited at higher rate exhibited increased twin density. In order to evaluate the mechanical behavior, tensile tests and nanoindentation experiments were conducted. The as-deposited film with partially twinned (~59%) microstructure exhibits linear elastic response with fracture strength of 1.4 GPa. Hardness of the film increased from 7.3 GPa to 9.36 GPa with increasing density of twinned grains.