Compressive flow behavior of Cu thin films and Cu/Nb multilayers containing nanometer-scale helium bubbles

Focused-ion-beam machined compression specimens were used to investigate the effect of nanometer-scale helium bubbles on the strength and deformability of sputter-deposited Cu and Cu/Nb multilayers with different layer thickness. The flow strength of Cu films increased by more than a factor of 2 due to helium bubbles but in multilayers, the magnitude of radiation hardening decreased with decreasing layer thickness. When the layer thickness decreases to 2.5 nm, insignificant hardening and no measurable loss in deformability is observed after implantation.

Research highlights
► Firstly micro-pillar compression technique has been used to measure the implanted metal films.
► The magnitude of radiation hardening decreased with decreasing layer thickness.
► When thickness decreases to 2.5 nm, no hardening and no loss in deformability after implantation.