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Some observations of slip lines on deformed copper whiskers
SOME
OBSERVATIONS
OF SLIP
LIhES
WHISKERS P.
ON DEFORMED
COPPER
*
CHARSLEYt
Observations on slip markings which are produced during the tensile deformation of copper whiskers indicate that visible cross-slip does not necessarily occur during the propagation of a Liiders band. A mechanism is proposed whereby such a band propagates as a result of the stress concentration between the slipped and unslipped regions of the whisker. QUELQUES
OBSERVATIONS
DE
LIGNES
CUIVRE
DE
GLISSEMENT
SUR
DES
BARBER
Les lignes de glissement qui apparaissent au tours de la d&formation par traction cuivre indiquent que le glissement croisb ne se produit pas n&zessairement pendant la bande de Liiders. L’auteur propose un m&anisme au tours duquel une telle bande se propager par suite d’une concentration de tensions & l’interface des regions de respectivement deformbes et non dbformhes. EINIGE
DE
DEFORMEES
GLEITLINIENBEOBACHTUNGEN
AN
AUS
VERFORMTEN
SUP des barbes de propagation d’une a la possibilite de la barbe qui sent’
FADENKRISTALLEN
KUPFER
Untersuchungen van Gleitspuren, die bei Zugversuchen auf Kupferwhiskern entstehen, zeigen, da0 sichtbare Quergleitung nicht notwendig bei der Ausbreitung eines Liidersbandes auftritt. Es wird ein Mechanismus vorgeschlagen, wodurch sich solch ein Band ausbreitet als Folge der Spannungskonzentration zwischen dem geglittenen und nicht geglittenen Gebiet des Whiskers.
The
plastic
deformation
of
copper
and
silver
Observations
were made with a low powered ( x 50)
whiskers has been reported in some detail by Brenner’l).
microscope
He found that after an initial yield point (usually at a
high powered
very
whisker had been removed
from the tensile machine.
In several
were removed
high stress) the whiskers
by the propagation
deformed
of one or more Liiders bands at
stresses of the order of one twentieth yield
stress.
It was proposed
Liiders
band
perfect
whisker
is propagated
of the initial
by Brenner through
by a double
multiple
propagation
that neither double slip mechanism
of
the
Liiders
before from
mechanism ;
slip on copper whiskers in some cases. which indicate
machine
that the
an essentially
cross-slip
this proposal was based on the observation
other
plastically
of multiple
are
stress-strain
whiskers with
of a number
(grown by the reduction
(loo),
measured
curves
in
(110) and
and (111)
observations
of
copper
of cuprous
iodide)
orientations made
some
systems
a varying
observed
was that,
slip
case of a (110) 2 per cent. band
it was assumed that
were also made
at a constant
on
orientation
slip on
stress and
slip was confined to several
systems
In
had
whisker
was
after a Liiders
at a stress constant
to within
Fig. 2 shows slip on two systems in the
between 2 and 4 kg/mm2.
the faces
although
but the slip was much more intense on one
best developed
between
but
conclusion
When the Liiders band propagated
stress,
band had propagated
of the slip lines
measurements
propagation
the
system than on any other. In Fig. 1 can be seen the slip which resulted in the
have been
the traces all resulted from slip on (111) planes.
from
the
in some cases, when the
had occurred,
case of a (100) orientation
some cases goniometric
band
when
The general
did occur
formed. By measuring the angles of the various slip traces it was found that for all three orientations the faces were {llO};
and under a
microscope
Liiders
these observations
several
at
this paper. The
after
any work-hardening.
only one system.
for the
reported
deformation
x800)
cases whiskers
no work-hardening
cross-slip nor any
band
plastic
(up to
Liiders band had propagated
Observations
is essential
during
propagated
whisker after the Liiders at
stresses
which
varied
In Fig. 2 it can be seen that
the “primary” slip extends along the whole length of the whisker and is intense in localized regions whilst
of the angles and these
were
slip also occurs
consistent with the indices of the faces deduced the slip trace angles.
from
patches. Some of the secondary slip is open to the interpretation that it is single cross-slip. Carbon replicas shadowed at tan-l & with goldpalladium were made of several deformed copper
*
Received June 25, 1959. t Research Laboratory, Associated Electrical Industries Limited, Aldermaston Court, Aldermaston, Berkshire. Present address: Battersea College of Technology, Physics Department, Battersea Park Road, London, S.W.ll. ACTA
METALLURGICA,
VOL.
8, JUNE
1960
whiskers.
on a secondary
system
These whiskers were deformed
in isolated
in tension in
a simple jig so that the Ltiders band had propagated 353
354
ACTA
FIG. 1. Slip
lines
on
along the whisker. about
a
(110) x 350
orientation
whisker.
were obtained
over a length of about
from
which
satisfactory
from two adjacent
0.1 mm.
faces
Slip was visible
VOL.
8,
FIG. 3. Carbon
In Fig. 3 is shown a whisker of
30 ,u mean diameter
micrographs
METALLURGICA,
on
1960
replica of whisker.
slip in strained x 8400
like the other whiskers, slip has given rise to only one slip trace some of the slip lines are of great depth. Several
slip lines, which
appeared
to be individual
slip steps, were about 0.8 ,u deep ; this is an appreciable
only one system for the whole area of both whisker
fraction
surfaces
between the lines was about 0.4 ,u.
investigated.
It was difficult
the step heights accurately slip lines were seen to end.
Replicas with
whiskers
were obtained
mean
diameters
Brenner
between
10 and 20 ,u; these showed slip on only one
mechanism.
The
can occur
spacings
between
the lines for
has
propagates
system.
mean
The mean spacing
DISCUSSION
300 A ; in some cases
from
other
of the whisker thickness.
on these replicas but they
were never more than about two
to determine
copper
proposed
that
the
Liiders
along the whisker by a double However, in copper,
cross-slip
band
cross-slip
is a process
at room-temperature,
which only
at
these three whiskers were 0.03, 0.1 and 0.3 ,u in order
high stresses such as can exist at the head of a piled up
of decreasing
group of dislocations
whisker diameter.
Some replicas were obtained
of a deformed
whisker
(see Schoeck and Seegerf2)).
11 ,u wide and 2 ,u thick and these present a strikingly
tions is necessary on the cross-slip system.
different
of whiskers
appearance
from
the
three
whiskers
of
larger mean diameter as is shown in Fig. 4. Although,
Fro. 2. Slip
lines
on
a (100) x 1050
orientation
whisker.
For
double cross-slip to occur, a further pile up of disloca-
resolvedshear
of (100)
orientation,
In the case
in particular,
the
stress factor is the same for the “cross-slip
FIG. 4. Carbon replica of a deformed diameter. x 8000
whisker of small
CHARSLEY:
system” the
SOME
as for the “primary
double
cross-slip
comparable
amounts
both slip systems. results indicate sarily
OBSERVATIONS
occur
slip system.”
mechanism
were
of slip would
SLIP
Thus
LINES
if
operative
be expected
In contrast to this the experimental
during
An alternative
the
Liiders
band
propagation.
mechanism,
more in agreement with
results,
the Liiders
as a result slipped
of the stress
between
the
whisker.
The observation
in zinc and cadmium
is that
and
unslipped
band
concentration regions
of the
of Liiders band propagation
whiskers
by Coleman
ON
DEFORMED
et &.t3)
COPPER
WHISKERS
355
supports this idea in so far as slip on any planes other than the basal planes is extremely
on
that visible cross-slip does not neces-
the experimental propagates
OF
unlikely.
ACKNOWLEDGMENTS
The author F.R.S.,
Director
wishes to thank
Dr. T. E. Allibone,
of this Laboratory,
for permission
to
publish this Paper. REFERENCES 1. S. S. BRENNER,J. Appl. Phys. 28, 1023 (1957). 2. G. SCHOECK and A. SEEGER in Rep. Bristol Conf. on Defects in Cqstalline Solids. p. 340. Physical Society, London (1955). 3. R.V. COLEMAN,B. PRICE and N. CABRERA, J. Appl. Phys. 28, 1361 (1957).
OBSERVATIONS
OF SLIP
LIhES
WHISKERS P.
ON DEFORMED
COPPER
*
CHARSLEYt
Observations on slip markings which are produced during the tensile deformation of copper whiskers indicate that visible cross-slip does not necessarily occur during the propagation of a Liiders band. A mechanism is proposed whereby such a band propagates as a result of the stress concentration between the slipped and unslipped regions of the whisker. QUELQUES
OBSERVATIONS
DE
LIGNES
CUIVRE
DE
GLISSEMENT
SUR
DES
BARBER
Les lignes de glissement qui apparaissent au tours de la d&formation par traction cuivre indiquent que le glissement croisb ne se produit pas n&zessairement pendant la bande de Liiders. L’auteur propose un m&anisme au tours duquel une telle bande se propager par suite d’une concentration de tensions & l’interface des regions de respectivement deformbes et non dbformhes. EINIGE
DE
DEFORMEES
GLEITLINIENBEOBACHTUNGEN
AN
AUS
VERFORMTEN
SUP des barbes de propagation d’une a la possibilite de la barbe qui sent’
FADENKRISTALLEN
KUPFER
Untersuchungen van Gleitspuren, die bei Zugversuchen auf Kupferwhiskern entstehen, zeigen, da0 sichtbare Quergleitung nicht notwendig bei der Ausbreitung eines Liidersbandes auftritt. Es wird ein Mechanismus vorgeschlagen, wodurch sich solch ein Band ausbreitet als Folge der Spannungskonzentration zwischen dem geglittenen und nicht geglittenen Gebiet des Whiskers.
The
plastic
deformation
of
copper
and
silver
Observations
were made with a low powered ( x 50)
whiskers has been reported in some detail by Brenner’l).
microscope
He found that after an initial yield point (usually at a
high powered
very
whisker had been removed
from the tensile machine.
In several
were removed
high stress) the whiskers
by the propagation
deformed
of one or more Liiders bands at
stresses of the order of one twentieth yield
stress.
It was proposed
Liiders
band
perfect
whisker
is propagated
of the initial
by Brenner through
by a double
multiple
propagation
that neither double slip mechanism
of
the
Liiders
before from
mechanism ;
slip on copper whiskers in some cases. which indicate
machine
that the
an essentially
cross-slip
this proposal was based on the observation
other
plastically
of multiple
are
stress-strain
whiskers with
of a number
(grown by the reduction
(loo),
measured
curves
in
(110) and
and (111)
observations
of
copper
of cuprous
iodide)
orientations made
some
systems
a varying
observed
was that,
slip
case of a (110) 2 per cent. band
it was assumed that
were also made
at a constant
on
orientation
slip on
stress and
slip was confined to several
systems
In
had
whisker
was
after a Liiders
at a stress constant
to within
Fig. 2 shows slip on two systems in the
between 2 and 4 kg/mm2.
the faces
although
but the slip was much more intense on one
best developed
between
but
conclusion
When the Liiders band propagated
stress,
band had propagated
of the slip lines
measurements
propagation
the
system than on any other. In Fig. 1 can be seen the slip which resulted in the
have been
the traces all resulted from slip on (111) planes.
from
the
in some cases, when the
had occurred,
case of a (100) orientation
some cases goniometric
band
when
The general
did occur
formed. By measuring the angles of the various slip traces it was found that for all three orientations the faces were {llO};
and under a
microscope
Liiders
these observations
several
at
this paper. The
after
any work-hardening.
only one system.
for the
reported
deformation
x800)
cases whiskers
no work-hardening
cross-slip nor any
band
plastic
(up to
Liiders band had propagated
Observations
is essential
during
propagated
whisker after the Liiders at
stresses
which
varied
In Fig. 2 it can be seen that
the “primary” slip extends along the whole length of the whisker and is intense in localized regions whilst
of the angles and these
were
slip also occurs
consistent with the indices of the faces deduced the slip trace angles.
from
patches. Some of the secondary slip is open to the interpretation that it is single cross-slip. Carbon replicas shadowed at tan-l & with goldpalladium were made of several deformed copper
*
Received June 25, 1959. t Research Laboratory, Associated Electrical Industries Limited, Aldermaston Court, Aldermaston, Berkshire. Present address: Battersea College of Technology, Physics Department, Battersea Park Road, London, S.W.ll. ACTA
METALLURGICA,
VOL.
8, JUNE
1960
whiskers.
on a secondary
system
These whiskers were deformed
in isolated
in tension in
a simple jig so that the Ltiders band had propagated 353
354
ACTA
FIG. 1. Slip
lines
on
along the whisker. about
a
(110) x 350
orientation
whisker.
were obtained
over a length of about
from
which
satisfactory
from two adjacent
0.1 mm.
faces
Slip was visible
VOL.
8,
FIG. 3. Carbon
In Fig. 3 is shown a whisker of
30 ,u mean diameter
micrographs
METALLURGICA,
on
1960
replica of whisker.
slip in strained x 8400
like the other whiskers, slip has given rise to only one slip trace some of the slip lines are of great depth. Several
slip lines, which
appeared
to be individual
slip steps, were about 0.8 ,u deep ; this is an appreciable
only one system for the whole area of both whisker
fraction
surfaces
between the lines was about 0.4 ,u.
investigated.
It was difficult
the step heights accurately slip lines were seen to end.
Replicas with
whiskers
were obtained
mean
diameters
Brenner
between
10 and 20 ,u; these showed slip on only one
mechanism.
The
can occur
spacings
between
the lines for
has
propagates
system.
mean
The mean spacing
DISCUSSION
300 A ; in some cases
from
other
of the whisker thickness.
on these replicas but they
were never more than about two
to determine
copper
proposed
that
the
Liiders
along the whisker by a double However, in copper,
cross-slip
band
cross-slip
is a process
at room-temperature,
which only
at
these three whiskers were 0.03, 0.1 and 0.3 ,u in order
high stresses such as can exist at the head of a piled up
of decreasing
group of dislocations
whisker diameter.
Some replicas were obtained
of a deformed
whisker
(see Schoeck and Seegerf2)).
11 ,u wide and 2 ,u thick and these present a strikingly
tions is necessary on the cross-slip system.
different
of whiskers
appearance
from
the
three
whiskers
of
larger mean diameter as is shown in Fig. 4. Although,
Fro. 2. Slip
lines
on
a (100) x 1050
orientation
whisker.
For
double cross-slip to occur, a further pile up of disloca-
resolvedshear
of (100)
orientation,
In the case
in particular,
the
stress factor is the same for the “cross-slip
FIG. 4. Carbon replica of a deformed diameter. x 8000
whisker of small
CHARSLEY:
system” the
SOME
as for the “primary
double
cross-slip
comparable
amounts
both slip systems. results indicate sarily
OBSERVATIONS
occur
slip system.”
mechanism
were
of slip would
SLIP
Thus
LINES
if
operative
be expected
In contrast to this the experimental
during
An alternative
the
Liiders
band
propagation.
mechanism,
more in agreement with
results,
the Liiders
as a result slipped
of the stress
between
the
whisker.
The observation
in zinc and cadmium
is that
and
unslipped
band
concentration regions
of the
of Liiders band propagation
whiskers
by Coleman
ON
DEFORMED
et &.t3)
COPPER
WHISKERS
355
supports this idea in so far as slip on any planes other than the basal planes is extremely
on
that visible cross-slip does not neces-
the experimental propagates
OF
unlikely.
ACKNOWLEDGMENTS
The author F.R.S.,
Director
wishes to thank
Dr. T. E. Allibone,
of this Laboratory,
for permission
to
publish this Paper. REFERENCES 1. S. S. BRENNER,J. Appl. Phys. 28, 1023 (1957). 2. G. SCHOECK and A. SEEGER in Rep. Bristol Conf. on Defects in Cqstalline Solids. p. 340. Physical Society, London (1955). 3. R.V. COLEMAN,B. PRICE and N. CABRERA, J. Appl. Phys. 28, 1361 (1957).