Abstract
AbstractNanocrystalline copper has been produced by two different techniques -- gas phase condensation and mechanical wear. Both nanocrystalline coppers have hardnesses and strain rate sensitivities that are greater than those of conventional, large-grained copper. These properties differences are tentatively explained on the basis of the two routes by which grain boundaries traditionally influence plastic deformation: by acting as barriers to dislocation glide, and by providing the vacancy sources and sinks necessary to facilitate diffusional flow. Additionally, there are notable differences in the mechanical properties of the two nanocrystalline coppers. Although the materials appear quite similar microstructurally, nanoindentation experiments show that the wear debris is 50% harder and 3 times more strain rate sensitive than the gas phase condensation-produced copper. These differences indicate that the microstructures are probably not as similar as first perceived, and that a previously overlooked microstructural feature may be influencing deformation in one or both of the materials.
Published Version
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