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Hrem Study of Fracture and Deformation Behavior of Nanostructured Thin Films

Published online by Cambridge University Press:  15 February 2011

Ming Ke
Affiliation:
Center for Mechanics, Materials, and Instabilities, Michigan Technological University, Houghton, Michigan 49931
Walter W. Milligan
Affiliation:
Center for Mechanics, Materials, and Instabilities, Michigan Technological University, Houghton, Michigan 49931
Stephen A. Hackney
Affiliation:
Center for Mechanics, Materials, and Instabilities, Michigan Technological University, Houghton, Michigan 49931
John E. Carsley
Affiliation:
Center for Mechanics, Materials, and Instabilities, Michigan Technological University, Houghton, Michigan 49931
Elias C. Aifantis
Affiliation:
Center for Mechanics, Materials, and Instabilities, Michigan Technological University, Houghton, Michigan 49931
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Abstract

Nanocrystalline gold and nickel thin films were prepared by both ion beam sputter deposition and electron beam evaporation techniques. The grain sizes were between 8–60 nm, depending on the processing. The deformation and fracture behavior of these nanostructural thin films were then investigated in a high resolution electron microscope (HREM) with atomic resolution. The behavior was a strong function of grain size. During slow strain rate deformation of small grain size materials (< 25 nm), nanopores formed and grew at grain boundary triple junctions in the front of crack and eventually linked with the main crack. The coalescence of the main crack with the growing nanopore, along with the elimination of the ligament between the two by a diffusive process, both indicated that diffusion played a role in deformation and fracture of these nanocrystalline thin films. In nickel films with larger grain sizes (> 25 nm), the cracks propagated in a mixed mode which was partially intergranular and partially transgranular. The transgranular propagation was crystallographic in nature, showing very fine, distinct crystallographic facets on the crack faces. It is suggested that a transition from intergranular propagation to a “cleavage-like” mechanism of propagation occurs with the increase of grain size.

Type
Research Article
Copyright
Copyright © Materials Research Society 1993

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References

REFERENCES

1 Birringer, R., Herr, U. and Gleiter, H., Trans. JIMIS-4, 27, 43, (1986)Google Scholar
2 National Materials Advisory Board, Research Opportunities For Materials with Ultrafine Microstructures, edited by National Research Council, Rep. NMAB-454, (National Academy Press, Washington D.C., 1989) pp.8.Google Scholar
3 Gleiter, H., Prog. Mater. Sci., 33, 223, (1991)CrossRefGoogle Scholar
4 Chokshi, A.H., Rosen, A., Karch, J. and Gleiter, H., Scripta Met. 23, 1679, (1989).Google Scholar
5 Nieman, G.W., Weertman, J.R., Siegel, R.W., Mat. Res. Soc. Proc. 206, 581, (1991).CrossRefGoogle Scholar
6 Suryanarayana, C. and Froes, F.H., Metall. Trans., 23A, 1071, (1992)CrossRefGoogle Scholar
7 Steeds, J.W., Introduction to Analytical Electron Microscopy. (Plenum Press, New York, 1979), p.393.Google Scholar
8 Palumbo, G., Thorpe, S.J. and Aust, K.T., Scripta Met. 24, 1647, (1990).Google Scholar