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The Crystallography of Cleavage Fracture in Al3 Sc

Published online by Cambridge University Press:  26 February 2011

J.H. Schneibel
Affiliation:
Oak Ridge National Laboratory, P.O.Box 2008, Oak Ridge, TN 37831–6114, USA Visiting Scientist at Max-Planck-Institut fuer Metallforschung, Institut fuer Werkstoffwissenschaft, D-7000 Stuttgart 1, FRG (until July 1991)
P.M. Hazzledine
Affiliation:
Oak Ridge National Laboratory, P.O.Box 2008, Oak Ridge, TN 37831–6114, USA
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Abstract

The intermetallic compound Al3Sc is a trialuminide with the LI2 structure, which deforms easily in compression at room temperature, with yield stresses around 100 MPa. In tension Al3Sc fractures transgranularly in a brittle manner. The predominant cleavage plane is {011}. Regions, which are flat within experimental resolution are only occasionally observed. Numerous cleavage steps, which are aligned in 3 major crystallographic directions, are found. Some of these steps consist of {111} or {001} planes, but others are not distinctly crystallographic. Plastic deformation involving dislocation motion or twinning may have occurred at some of these steps. Reactions between different types of steps are also observed. One type of cleavage pattern found is strikingly similar to the typical appearance of fracture surfaces of fcc brass and Cu3Au after stress corrosion cracking. However, this particular pattern is only rarely observed in Al3Sc. Our observations indicate that an interpretation of cleavage fracture in Al3Sc in terms of surface energies alone is unlikely to be successful. A full understanding of the fracture morphology of Al3Sc will require detailed atomistic simulations taking dislocation motion and twinning into account.

Type
Research Article
Copyright
Copyright © Materials Research Society 1991

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References

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