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e-beam melted icosahedral Al–Mn surface layers: Microstructures and phason defects

Published online by Cambridge University Press:  31 January 2011

D. M. Follstaedt  and
J. A. Knapp
D. M. Follstaedt
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185-5800
J. A. Knapp
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185-5800
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Abstract

The microstructure of icosahedral Al(Mn) in melt-quenched surface alloys has been characterized with TEM. Single-phase alloys with 20 at. % Mn show angular misorientations (up to ∼7°) across internal boundaries radiating from the nucleation centers of grains. Lowering the Mn content results in fcc Al at grain boundaries and between branches of the icosahedral grains; the presence of Al-rich liquid around growing grains apparently eliminates the misorientations seen with 20 at. % Mn. The grains have a dense distribution of dislocation-like defects, but have sufficient orientational order to exhibit well-defined diffraction contours. Weak reflections in diffraction patterns from small areas (0.7 μm) of grains exhibit deviations from exact icosahedral symmetry positions which were analyzed to evaluate a phason strain tensor and characterize misordering defects in the quasicrystalline structure. A negative matrix element (m ≍–0.05) for a tensor axis along a twofold icosahedral axis accounts for most of the distortions in these patterns and those from other melt-quenched icosahedral Al(Mn) and Al(Mn, Si) alloys; this dominant element lowers the symmetry to D2. This axis is nearly perpendicular to the growth direction, which suggests that the misordering is due to rapid growth during the quench; however, the D2 distortion may also result from an elastic instability predicted for icosahedral phases. Distortions in Al(Cr, Ru) can be fit with a similar tensor but with m>0. Thus the phason character identified here may apply to other aluminum-transition metal icosahedral phases as well.

Type
Articles
Information
Journal of Materials Research , Volume 4 , Issue 6 , December 1989 , pp. 1398 - 1416
Copyright
Copyright © Materials Research Society 1989

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References

REFERENCES

1Shechtman, D.Blech, I.Gratias, D. and Cahn, J. W.Phys. Rev. Lett. 53, 1951 (1984).CrossRefGoogle Scholar
2Knapp, J. A. and Follstaedt, D.M.Phys. Rev. Lett. 55, 1591 (1985).CrossRefGoogle Scholar
3Follstaedt, D. M. and Knapp, J. A.Phys. Rev. Lett. 56, 1827 (1986).CrossRefGoogle Scholar
4Budai, J. D.Tischler, J. Z.Habenschuss, A.Ice, G. E. and Elser, V.Phys. Rev. Lett. 58, 2304 (1987); see also J. D. Budai and M. J. Aziz Phys. Rev. B33, 2876 (1986).CrossRefGoogle Scholar
5Cahn, J. W.MRS Bulletin XI, 9 (March/April, 1986).Google Scholar
6Levine, D. and Steinhardt, P. J.Phys. Rev. Lett. 53, 2477 (1984).CrossRefGoogle Scholar
7Stephens, P.W. and Goldman, A.I.Phys. Rev. Lett. 56, 1168 (1986).CrossRefGoogle Scholar
8Shechtman, D. and Blech, I.Metall. Trans. A16A, 1005 (1985).Google Scholar
9Levine, D. and Steinhardt, P.J.Phys. Rev. B34, 596 (1986); J. E. S. Socolar and P.J. Steinhardt Phys. Rev. B34, 617 (1986).Google Scholar
10Guyot, P. and Audier, M.Phil. Mag. B52, L15 (1985); Phil. Mag. B53, L43 (1986).Google Scholar
10Steinhardt, P.J.Phys. Rev. Lett. 57, 2769 (1986) (comment); P. W. Stephens and A.I. Goldman Phys. Rev. Lett. 57, 2770 (1986) (response).CrossRefGoogle Scholar
12Knapp, J. A. and Follstaedt, D. M.Nucl. Instrum. Methods B19/20, 611 (1987).Google Scholar
13Knapp, J. A. and Follstaedt, D. M.Phys. Rev. Lett. 58, 2454 (1987).CrossRefGoogle Scholar
14Follstaedt, D. M. and Knapp, J. A.Mat. Res. Soc. Symp. Proc. 74, 333 (1987).Google Scholar
15Socolar, J.E.S.Lubensky, T.C. and Steinhardt, P.J.Phys. Rev. B34, 3345 (1986).Google Scholar
16Penrose, R.Bull. Inst. Maths. Its Appl. 10, No. 7/8, 266 (1974).Google Scholar
17Goldman, A.I. and Stephens, P.W.Phys. Rev. B37, 2826 (1988-2011).Google Scholar
18Lubensky, T. C.Socolar, J.E. S.Steinhardt, P.J.Bancel, P. A. and Heiney, P. A.Phys. Rev. Lett. 57, 1440 (1986).CrossRefGoogle Scholar
19Bancel, P.A. and Heiney, P. A.J. Phys. (Colloque C3, suppl. #7) 47, C3–341 (1986).Google Scholar
20Hiraga, K. and Hirabayashi, M.J. Electron Micros. 36, 353 (1987).Google Scholar
21Socolar, J.E.S. and Wright, D.C.Phys. Rev. Lett. 59, 221 (1987).CrossRefGoogle Scholar
22Knapp, J. A. and Picraux, S. T.J. Appl. Phys. 53, 1492 (1982); J. A. Knapp J. Appl. Phys. 58, 2584 (1985).CrossRefGoogle Scholar
23Schaefer, R.J.Bendersky, L. A.Shechtman, D.Boettinger, W. J. and Biancaniello, F. S.Metall. Trans. A17A, 2117 (1986).Google Scholar
24Moran, M. Sandia Report No. SAND88-0133, Sandia National Laboratories, Albuquerque, NM 87185-5800.Google Scholar
25Gronsky, R.Krishnan, K. H. and Tanner, L. in Proc. of the 43rd Annual Meeting of the Electron Microscopy Society of America, edited by Bailey, G. W. (San Francisco Press, San Francisco, CA, 1985), p. 34.Google Scholar
26Sastry, G. V. S. and Ramachandrarao, P.J. Mater. Res. 1, 247 (1986).CrossRefGoogle Scholar
27Cahn, J.W.Shechtman, D. and Gratias, D.J. Mater. Res. 1, 13 (1986).Google Scholar
28Bancel, P. A.Heiney, P. A.Stephens, P.W.Goldman, A.I. and Horn, P.M.Phys. Rev. Lett. 54, 2422 (1985).CrossRefGoogle Scholar
29Elser, V.Phys. Rev. B32, 4892 (1985).Google Scholar
30Our program was written for a Hewlett-Packard Model 217 personal computer; a printout will be supplied upon request.Google Scholar
31Socolar, J.E.S.J. Phys. (Colloque C3, suppl. #7) 47, C3–217 (1986).Google Scholar
32Taneka, M.Terauchi, M.Hiraga, K. and Hirobayashi, M.Ultra-microscopy 17, 279 (1985).Google Scholar
33Horn, P.M ., Malzfeldt, W.DiVincenzo, D. P.Toner, J. and Gambino, R., Phys. Rev. Lett. 57, 1444 (1986).Google Scholar
34Bendersky, L. A. and Kaufman, M. J.Phil. Mag. B53, L75 (1986).Google Scholar
35Jaric, M. V. and Mohanty, U.Phys. Rev. Lett. 58, 230 (1987).CrossRefGoogle Scholar
36Biham, O.Mukamel, D. and Shtrikman, S. (unpublished research, discussed in Ref. 35).Google Scholar
37Socolar, J.E. S. presentation at conf. on Quasicrystals and Related Structures, Santa Barbara, CA, Jan. 11–15, 1988.Google Scholar