"Artificially Layered Al/Cu Nanocomposites Fabricated by Jet Vapor Deposition"
Proc., Symposium on Structure and Properties of Multilayered Thin Films, Vol. 382, Eds. T.D. Nguyen et al., MRS, San Francisco, pp. 113-122, 1995.
Aluminum and copper nanolaminates have been fabricated using a novel Jet Vapor Deposition (JVD) process. Laminates with a total thickness of 10 mm were made by depositing alternating layers of approximately equal thicknesses of copper and aluminum onto preheated silicon wafers at a substrate temperature of ~140oC. The layer thicknesses were systematically varied between 20 nm and 1000 nm. The microstructure and properties of the laminates were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nanoindentation methods. TEM has shown that the laminates have a strong {111} texture. The hardness results show that above a critical layer thickness of approximately 60 nm, the yield strength of the composites varies inversely with the layer thickness, while the strength of nanolaminates with layer thicknesses smaller than the critical thickness is better explained by the Koehler model. An alternative model recently proposed by Embury and Hirth fits the data equally well.