As
we
have
seen
so
far
,
materials
have
defects
at
the
atomic
scale
.
These
____________________
allow
solute
atoms
to
stay
in
positions
normally
occupied
by
solvent
____________________
,
as
on
____________________
solid
solutions
;
but
,
if
energy
is
favorable
and
the
size
of
the
solute
is
small
compared
with
the
solvent
interstitial
space
(
empty
space
between
atoms
)
,
____________________
solid
solutions
can
be
formed
.
Under
some
circumstances
,
solid
solutions
exist
for
some
compositions
.
As
for
sugar
,
you
can
dilute
sugar
in
water
.
If
you
add
more
and
more
sugar
,
you
would
saturate
the
____________________
.
If
you
add
more
sugar
,
the
excess
in
sugar
will
____________________
as
a
second
phase
.
This
is
also
true
for
solid
____________________
;
they
can
exist
over
a
range
of
compositions
and
,
in
many
cases
,
you
can
have
one
material
with
different
phases
that
co
-
exists
.
One
example
of
this
kind
of
material
is
the
steel
.
At
the
atomic
level
,
steel
is
a
mixture
of
____________________
and
____________________
.
But
microscopically
,
steel
is
formed
by
two
or
more
phases
.
A
steel
that
have
been
slowly
cooled
,
normally
will
show
a
mixture
of
Fe
-
?
(
____________________
)
and
Fe3C
(
intermetallic
compound
,
____________________
____________________
)
.
This
mixture
is
called
perlite
.
But
if
the
steel
is
cooled
less
slowly
,
it
would
form
bainita
(
also
a
mixture
between
phases
)
,
and
if
the
steel
is
quickly
cooled
to
room
temperature
(
quenching
)
it
would
form
____________________
.
In
the
three
cases
,
the
steel
composition
is
the
same
,
but
the
cooling
rate
determines
the
final
microstructure
.
