Berlin 2005 – wissenschaftliches Programm
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M: Metallphysik
M 11: Symposium Complex Metallic Alloys III
M 11.3: Vortrag
Freitag, 4. März 2005, 18:00–18:15, TU H1058
Plastic behaviour of polycrystalline β -Al-Mg — •Michael Feuerbacher and Marc Heggen — Institut für Festkörperforschung Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
β −Al3Mg2 is a cubic complex metallic alloy phase with
particularly large lattice constants of 28.2 Å and 1168 atoms per
unit cell. The main structural elements are Friauf polyhedra arranged in
fivefold coordinations. The material is potentially interesting for
technological applications since it is a lightweight alloy (2.2 g/cm3)
and it congruently solidifies from the melt.
We have performed uniaxial plastic deformation experiments on
polycrystalline β -Al-Mg in the temperature range from 300 to
400 deg C at strain rates of 10 − 4 and 10 − 5 s − 1. The material
is highly ductile and shows strong continuous work softening after the upper
yield point. We have performed stress-relaxation and temperature-cycling
tests to determine the thermodynamic activation parameters of the
deformation process. Strongly stress dependent activation volumes in the
range of 0.3 to 2.2 nm3 and a stress exponent of about 3.5 were found.
The activation enthalpy assumes rather high values of 3 to 5 eV. After
deformation the samples show strong shear bands oriented at 45 deg with
respect to the compression axis.