We compare the indentation hardness of crystal/crystal (C/C) Cu/Zr multilayers and the crystal/amorphous (C/A) Cu/Cu-Zr multilayers with equal individual layer thicknesses spanning from 1 to 200. nm. Both systems show similar layer thickness dependent evolution of hardness. At smaller layer thickness the C/C multilayers show softening, while no softening is observed in the C/A multilayers. The layer thickness dependent hardness is quantitatively estimated by using dislocation models. The significance of crystalline (Zr) layer and amorphous (Cu-Zr) layer on plastic deformation mechanisms is discussed.
Bibliographical noteFunding Information:
This research was supported by the 973 Program of China (Grant No. 2010CB631003 ), the 111 Project of China ( B06025 ) and t he National Natural Science Foundation of China ( 50971097 ). G.L thanks the support of Fundamental Research Funds for the Central Universities and J.Y.Z thanks the financial support of China Scholarship Council (CSC) . X.Z acknowledges financial support by the US NSF-DMR Metallic Materials and Nanostructures Program , under Grant No. 0644835 . J.C acknowledges the NSFC (Grant No. 50801036 ) for partial financial support.
- Crystalline/amorphous multilayers
- Crystalline/crystalline multilayers