Creep behavior in dilute nanocrystalline thin-film aluminum alloys

초록

Thermal creep of nanocrystalline (nc-) 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, whether precipitation had occurred, and the sample hardness. The range of activation energies and stress exponents for the various samples were 0.44 +/- 0.05 eV and 0.99 +/- 0.06, respectively, strongly suggesting a grain-boundary diffusional creep mechanism.

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