Ultra-Hard Nanostructured Al-Si Thin Films
We show that it is possible to use high rate co-evaporation of Al and Si onto room temperature substrates to achieve a novel two-phase nanoscale microstructure. These nanocomposites have a hardness as high as 4GPa (Al-23at.%Si), and display noticeable plasticity. Films with compositions of Al-12at.%Si and pure Al (used as baseline) were analyzed using transmission electron microscopy (TEM). The scale of the Al-12at.%Si microstructure is an order of magnitude finer compared to that of pure Al films. It consists of a dense distribution of spherical nanoscale Si particles separating irregularly-shaped small Al grains. These new structures may have a mechanical performance advantage over conventional single phase nanomaterials due to the role of the dispersed hard phase in promoting strain hardening.
Dragan P. Uskokovic, Slobodan K. Milonjic, Djan I. Rakovic
V. Radmilović et al., "Ultra-Hard Nanostructured Al-Si Thin Films", Materials Science Forum, Vol. 494, pp. 13-18, 2005