Stacking fault and partial dislocation dominated strengthening mechanisms in highly textured Cu/Co multilayers

• We observe high density inclined stacking faults in (1 0 0) textured FCC Co, and high density twins in (1 1 1) textured FCC Co.
• We discover large difference in size dependent strengthening in (1 0 0) and (1 1 1) textured Cu/Co multilayers.
• The impact of partial dislocations on deformation mechanisms of multilayers is discussed.

We investigate the interfaces and mechanical properties of sputtered, highly (1 0 0) and (1 1 1) textured Cu/Co multilayers. In (1 0 0) Cu/Co multilayers, Co has primarily face-centered-cubic (FCC) structure and high density of inclined stacking faults (SFs). In contrast in (1 1 1) textured Cu/Co, dependent on layer thickness, high density SFs and twins parallel to layer interface are observed. When individual layer thickness, h, is a few nanometers, both systems have fully coherent FCC interface. (1 1 1) Cu/Co has similar size dependent strengthening and peak hardness compared to (1 1 1) Cu/Ni multilayers. The peak strength of (1 0 0) Cu/Co may be dominated by the transmission of partial dislocations across interface, and hence it is lower than the peak strength of (1 0 0) Cu/Ni, which is dictated by transmission of full dislocations across interfaces.