Es erkennt hier eine sprudelnde Quelle. Wir auch. - ULV Leoben ...

158
A study of the modification of
Al-Si & Al-Mg 2 Si eutectic
An investigative study of heterogeneous nucleation using an entrained droplet
technique in an Al-Si alloy & the solidification microstructure and morphology of
Mg 2 Si in an Al-Mg-Si alloy by using a Bridgman furnace.
Al-13.1%Mg 2 Si near eutectic alloys were prepared
in a Dietz mould using high purity Al, Si & Mg. Additions
of Sr & Y in the form of master alloys were
made to modifiy the morphology of Mg 2 Si. With the
addition of Sr the Mg 2 Si morphology appears to be
flake or block-like while with the addition of Y the
morphology changes to fine fibres as can be seen
from the deep etched samples (see Fig. 2). Planned
future work includes the use of a Bridgman furnace
to see the effect on the solidification microstructure
and eutectic morphology using different growth
velocities and temperature gradients. Al-Al 3 Ni regular
eutectic will be use to confirm the steady state
growth (see Fig. 2).
Muhammad Zafar
Lehrstuhl für Gießereikunde
an der MUL seit: 2007
Email: muhammad-zafar.zarif@stud.unileoben.ac.at
institute.unileoben.ac.at/giessereikunde
Zur Person:
M.Sc Eng. from PIEAS, Pakistan
derzeit: Ph.D. Student at Chair of Casting Research (MUL)
A high purity Al-Si master alloy was prepared by arc
melting under high vacuum to reduce contamination.
The alloy was then melt-spun on a rotating Cu wheel
to produce a ribbon 3 mm wide and 85 µm thick. The
DSC traces obtained from the ribbons showed two
exothermic peaks. The first peak corresponds to the
solidification of grain boundary eutectic, while the
second peak corresponds to solidification of eutectic
droplets in the Al matrix (see Fig. 1). A brightfield
TEM image of an entrained droplet (see Fig. 1).
Forschungspartner:
Forschungsschwerpunkte:
Solidification, especially modification of Al-Si and
Al-Mg-Si alloys