Résumé:
In
this
work
, we
have
undertaken
the
study
of
two
sheets
AlMgSi.
These
arouse
great
interest
for
their
privileged
use
in
the
automotive
and
the
aerospace
industrie
.
The
aim
of
the
present
work
is the
study
of
transformations
reactions
of
phases
and
the
influence
of
natural
ageing
on
the
mechanical
properties
of
AlMgSi
alloys
.
For
the
characterization
of
these
materials,
we
have
used
various
experimental
techniques
such
as
differential
calorimetric
analysis
(DSC),
optical
microscope,
microhardness
measurements,
X-rays
diffraction
and
dilatometry.
DSC
stud
ies
enabled
us
to
follow
the
transformation
of
the
various
phases
of
the
sequence
of
precipitation
in
these
alloy
s. The
microstructure
of
alloys
was
characterized
by
optical
microscopy.
The
characterization
by
diffraction
of
x-rays
did
not
highlight
the
presence
of
another
phase
in
add
ition
to
the
matrix
α-aluminium;
the
non
detection
of
other
phase
could
be
due
to
its
small
volume
fraction.
But,
the
use
of
x ray
diffraction
revealed
the
presence
of
anisotropy,
as
the
sheets
have
been
rolled.
The
microhardnes
s measurements
showed
that
the
excess
of Mg
does
not
improve
the
mechanical
properties
of
AlMg
Si
alloys.
The
dilatometric
results
confirmed
the
presence
of
an
anisotrop
y.
The
thermal
expansion
coefficient
measurements
differ
from
one
direction
to
another
and
from
one
alloy
to
anot
her
.
