Berlin 2005 – scientific programme
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M: Metallphysik
M 11: Symposium Complex Metallic Alloys III
M 11.4: Talk
Friday, March 4, 2005, 18:15–18:30, TU H1058
Structural defects in orthorhombic Al13Co4 — •Dewei Deng, Marc Heggen, and Michael Feuerbacher — Institut für Festkörperforschung Forschungszentrum Jülich GmbH
Orthorhombic Al13Co4 is a complex metallic alloy phase with 101
atoms per unit cell. The lattice constants are a = 0.8165(1)nm, b = 1.2352(1)nm,
c = 1.4451(1)nm and it has a of Pmn21 space group. It is structurally
isomorphic to the well investigated phase ξ ’-Al-Pd-Mn in the sense that
the [1 0 0] lattice direction of orthorhombic Al13Co4 can be
described using similar types of hexagon-tiling arrangements as for the [0 1
0] direction of ξ ’-Al-Pd-Mn. We have grown single crystals of
orthorhombic Al13Co4 using the Bridgman technique. In the as grown
material defect analyses were performed by means of transmission electron
microscopy.
The material contains planar defects terminated by dislocations. The planar
defects were identified as stacking faults. By means of tilting series in
the transmission electron microscope the plane normal of the faults was
determined as parallel to the [0 0 1] lattice direction. We have performed
two beam Bragg-contrast exit nction experiments and determined the
strain-field direction of the planar faults and the terminating dislocations
as parallel to the [3 2 0] direction. Hence we can conclude that
partial-dislocation motion on (0 0 1) lattice planes by pure glide takes
place in orthorhombic Al13Co4