Creep in Nanocrystalline Thin-Film Al Alloys

초록

The high strength of nanocrystalline metals makes them ideal candidates for a wide range of technologically important applications. Thin films are increasingly in many industrial applications and nanocrystalline Al alloys are particularly useful for thin-film applications as they are inherently resistant to oxidation and corrosion. In this work, thermal creep of nanocrystalline Al and dilute nc-Al alloys (Al-Sc, Al-Sb, and Al-W) was investigated at various temperatures using an in-situ thin-film bulge method. Most samples were pre-annealed prior to creep testing to stabilize the microstructure; for Al-Sc, however, measurements were performed both with and without pre-annealing. Pre-annealing led to precipitation at the grain boundaries for Al-Sc and Al-Sb, but not Al-W. The creep data for all samples were analyzed with respect to the sample grain size and the sample hardness. The range of activation energies and stress exponents for the various samples strongly suggesting a grain-boundary diffusional creep mechanism.