MECHANICAL-PROPERTIES OF CU AG MULTILAYERED COMPOSITES/

Cu-Ag multilayered nanocomposites, as well as pure copper samples, wer e made by electrodeposition using a single-bath cyanide solution. Two groups of composites with different bi-layer thickness values (about 3 30 and 110 nm, respectively) were produced. The thickness of the silve r layers (approximate to 10 nm) was the same in all samples. Annealing was conducted to investigate the stability of microstructure at low t emperatures. The results of this study showed that the as-deposited la minated composites have a much higher strength relative to the electro deposited pure copper. However, the effect of the copper layer thickne ss on strength was not significant. Annealing at 150 degrees C caused the specimens in both groups to lose their strength to the level of pu re copper specimens. Based on the microstructural and mechanical prope rties analyses, it is suggested that the high strength of the electrod eposited Cu/Ag laminated composites arises from the refinement of grai ns in the copper layers, the resistance of the silver layers to plasti c deformation and the existence of coherency stresses at the layer int erfaces. Annealing at 150 degrees C results in a loss of strength owin g to the recovery of microstructure, copper grain growth and consequen t relaxation of interfacial stresses. (C) 1998 Elsevier Science S.A. A ll rights reserved.