ON THE PROPERTIES OF OXIDIZED AND
REDUCED COPPER SAMPLES USED FOR
ELECTRON IRRADIATION EXPERIMENTS IN THE
kHz-RANGE
U. Gratzel, K. Lücke, G. Sokolowski, B. Wantzen
To cite this version:
U. Gratzel, K. Lücke, G. Sokolowski, B. Wantzen. ON THE PROPERTIES OF OXIDIZED
AND REDUCED COPPER SAMPLES USED FOR ELECTRON IRRADIATION EXPERIMENTS IN THE kHz-RANGE. Journal de Physique Colloques, 1983, 44 (C9), pp.C9-533-C9537. <10.1051/jphyscol:1983978>. <jpa-00223428>
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JOURNAL DE PHYSIQUE
Colloque C9,supplkment au n012,Tome 44,dkcembre 1983
page C9-533
ON THE PROPERTIES OF OXIDIZED AND REDUCED COPPER SAMPLES USED FOR
ELECTRON IRRADIATION EXPERIMENTS IN THE kHz-RANGE
U. Gratzel, K. Liicke, G. Sokolowski and B. Wantzen
Institut far AZZgemeine MetaZZkunde und MetaZZphysik der RWTH Aachen, F.R.G.
Abstract - Undeformed oxidized and reduced samples are
compared with respect to their pinning behaviour after
electron-irradiation, to the existence of Bordoni peaks
and to the amplitude dependence of internal friction.
I
-
INTRODUCTION
For copper it has been reported that the internal friction behaviour
after cold-work depends strongly on the atmosphere used for the recrystallization anneal / I / . The oxidized and reduced state of copper
had been obtained after anneals at 1173 K in corresponding atmospheres.
For the investigation of internal friction in the Hz-range after electron-irradiation at 130 K such samples have been deformed and before
irradiation the deformation-induced point defects and the Hasiguti
peaks caused by them have been annealed at 400 K. Thus the irradiation
effects could be increased /2/. However, for irradiations at 4.2 K a
deformation-induced Bordoni-peak, which does not recover at 400 K, would
make the quantitative evaluation of pinning experiments by the GranatoLucke theory impossible. Therefore, first irradiation experiments with
undeformed oxidized and reduced copper samples annealed at 1173 K will
be reported here.
I1
- EXPERIMENTAL PROCEDURE
For the preparation of the samples in the first place rods of 99.999%
ASARCO-copper with 9 mm diameter were rolled to a thickness of 3 mm.
Then blocks of 21x6~3mm were cut and 7 mm of the blocks were milled
down to give a section 7 mrn long, 2 mm broad and 0.15 mm thick. This
milled section was the active part of the sample, a vibrating cantilever beam oscillating flexurally, the remaining thick portion was
merely used as a clamping block. This preparation technique corresponds
to that used by Sosin et al. / 3 / . The as-machined samples were annealed
for 2 h at 1173 K and 1023 K in 0.13 Pa air (0-samples) or 1x105 Pa CO
(R-samples). Before and after the anneals the samples were etched
electrolytically in 50% H3P04. Then the thick portion of the sample,
possessing two holes, was bolted to a sample holder, the temperature
of which could be varied between 4.2 and 323 K. Opposite to the free
end of the sample was an insulated electrode to detect the vibrations
of the sample by frequency-modulation of a.120 MHz-oscillator. This was
at 78 K to reduce the noise. To excite the vibrations of about 2 kHz
an alternating voltage of the sample frequency and a polarizing voltage
of 10 V were used. The alternating voltaqe was controlled automatically
in a closed loop to maintain the amplitude of oscillation constant,
thus representing a relative measure of decrement. The maximum strain
amplitude was varied between 3x1 o - ~and 5x1 0-7. The polarizing voltage
of 10 V caused a static strain amplitude of 3x10-~.With 300 V the
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1983978
JOURNAL DE PHYSIQUE
C9-534
static strain amplitude could be increased to 3x10-~ (used only for
sample R1173). 3 MeV-electrons were used for the irradiations. A dose
of 5x1 o1 electrons/cm2 produced a Frenkel defect concentration of
3x1 o - ~ .After a dose of 5x1 017 electrons/cm2 the dislocations are
pinned so strongly that they no longer contribute to internal friction
(background dose)
.
/
I
1710
-4,
.
R 1173
0
~=86r10-'
Dose
,T,
0
-
0
5x10"
I
1
"=--%.B
v 5x10"
'I
E.
B\,e-
2?b80
c
a,
42K
323 K
*
a'
'
.
'
'1
j
0
1650
1630,
1W
200
g\
a\
30
Temperature lK1
F i e : Temperature dependence of
-
frequency for sample R.1173: before irradiation (squares), after
5x1 015 electrons/cm2 at 4.2 K
(circles) and after the background
dose of 5x1 o1 electrons/cm2 (triangles).
I11
Fig.2: Amplitude dependence
of frequency for sample
R.1173 at 30 and 323 for
polarizing voltages of 10 V
(open symbols) and 300 V
(full symbols)
.
- EXPERIMENTAL RESULTS
The reduced sample R.1173 was annealed at 1173 K and during the
measurements and irradiations a polarizing voltage of 300 V was used.
Fig.1 depicts the temperature dependence of frequency for this sample:
before irradiation (squares), after 5x1 o1 electrons/cm2 (circles) and
after the background dose of 5 x 1 0 ~
electrons/cm2
~
(triangles). The
coincidence of all three curves indicates that there is no irradiation
effect. In Fig.2 the amplitude dependence of this sample is given for
two temperatures and two polarizing voltages. At 30 K the static strain
amplitude of 3x1 o - ~(300 V) decreases the modulus by 0.85% with respect
to the 10 V-curves. For 323 K the effect is smaller because both measurements (10 V and 300 V) were performed at slightly different temperatures. So the temperature dependence of the modulus decreases the
effect. The observed modulus decrease due to the bowing-out of the
dislocations under the static stress indicates that there is a sufficient modulus defect under these conditions. Furthermore, one can conclude from the weak amplitude dependence, that for the statically
small (10 V) and large (300 V) bow-outs of the dislocations their mean
free loop length is rather small.
The temperature dependence of decrement for the oxidized sample
0.1173/2 (annealed at 1 1 73 K) is depicted in Fig.3 (full symbols).
One recognizes a marked Bordoni-peak at about 90 K. -The reduction
of the annealing temperature to 1023 K for sample 0.1023/2 (open
symbols) gives a temperature dependence of decrement without a
Bordoni-peak. For both annealing temperatures the oxidized samples
show an irradiation effect /4/.
Fig.3: Temperature dependence of decrement for sample
0.11 73/3 (full symbols) and
for sample 0.1023/2 (open
symbols).
Temperature LKI
2168i---------------'
10-
18
16~
lo1
10-~
Strain Amplitude E
Strain Amplitude E
~ i . 5g: AmpEit ude dependence
of frequency for sample
0.1023/3 at different temperatures.
Fig.4: Amplitude dependence
of frequency for sample
R.1023/2 at different temperatures.
For the reduced samples annealed at 1023 K dislocation pinning is
observed after irradiation at 4.2 K / 4 / . The amplitude dependence
of frequency for such a sample is shown for R.1023/2 in Fig.4. It
can be seen that for low temperatures (T = 30 K ) the amplitude dependence is very weak, but for high r temperatures (T = 323 K ) it
starts at amplitudes of about 1x10- rl For the oxidized sample 0.1023/3
(annealed at 1023 K ) the amplitude dependence of frequency is givene8
in Fig.5. One recognizes that for all temperatures below about 6x10
the modulus is amplitude independent.
.
IV
- DISCUSSION
The state of the sample R.1173 is characterized by a residual resistivity ratio RRR = 564, e.g. a high concentration of homogeneously
dispersed single impurity atoms. However, the missing irradiation
effect for this sample cannot be explained by a complete pinning of
the dislocations by these impurity atoms. For the sample has been
irradiated and measured in a statically bowed-out position of the
dislocations corresponding to a maximum statical strain amplitude of
JOURNAL DE PHYSIQUE
C9-536
.
3x1 o - ~ (300 V ) I n t h i s s t a t e t h e r e e x i s t s a modulus d e f e c t of 0.85%
w i t h r e s p e c t t o a s t a t i c a l bow-out of 3x1 0-* (1 0 V ) , i n d i c a t i n g t h a t
t h e r e i s a s u f f i c i e n t c o n t r i b u t i o n of t h e d i s l o c a t i o n s t o t h e modulus
and d i s l o c a t i o n p i n n i n g s h o u l d be d e t e c t a b l e a f t e r i r r a d i a t i o n . Howe v e r , t h e weak a m p l i t u d e dependence of t h i s sample c o r r e s p o n d s t o
s h o r t l o o p l e n g t h s o f t h e d i s l o c a t i o n s . To o b t a i n a c e r t a i n mean numb e r o f p i n n i n g p o i n t s p e r l o o p more p o i n t d e f e c t s a r e n e c e s s a r y t h a n
f o r l o n g e r loops. But t h e f a c t t h a t even a t t h e background d o s e no
measurable p i n n i n g e f f e c t could be observed r e q u i r e s an a d d i t i o n a l
assumption: The number of p o i n t d e f e c t s a r r i v i n g a t t h e d i s l o c a t i o n s
i s t o o s m a l l . T h i s reduced sample h a s t h e h i g h e s t c o n c e n t r a t i o n of
i m p u r i t y atoms i n t h e l a t t i c e , which must a c t a s t r a p p i n q c e n t e r s f o r
p o i n t d e f e c t s . Thus t h i s t r a p p i n g of d e f e c t s a n d t h e s h o r t l o o p l e n q t h
can account f o r t h e m i s s i n g p i n n i n g e f f e c t . A f t e r an a n n e a l a t
1023 K t h e reduced samples show a v a l u e RRR = 816. Obviously, t h e
s m a l l e r c o n c e n t r a t i o n o f t r a p p i n g c e n t e r s and a l o n g e r l o o p l e n g t h
o f t h e d i s l o c a t i o n s g i v e s a p i n n i n g e f f e c t . However, t h i s s t a t e of
t h e sample i s c h a r a c t e r i z e d by an am l i t u d e dependence of i n t e r n a l
f r i c t i o n s t h a t s t a r t s a t a b o u t I X I O - ~a t 323 K. T h i s means t h a t an
a p p l i c a t i o n o f t h e amplitude-independent Granato-Lucke t h e o r y i s
o n l y p o s s i b l e f o r measurements a t v e r y low a m p l i t u d e s .
The o x i d i z e d sample ( F i g . 3 ) shows a Bordoni-peak a f t e r t h e r e c r y s t a l l i z a t i o n a n n e a l a t 1173 K . The e x i s t e n c e o f t h i s peak i s
n o t due t o a c c i d e n t a l deformations d u r i n g t h e h a n d l i n g of t h e
samples, because i t n e v e r a p p e a r s i n t h e reduced samples, which a r e
handled i n t h e same way. The Bordoni-peak should b e due t o s u r f a c e
o x i d a t i o n e f f e c t s d u r i n g t h e a n n e a l s . Oxide i s l a n d s have been obs e r v e d on t h e s u r f a c e of o x i d i z e d samples used f o r i n t e r n a l f r i c t i o n
experiments / 5 / . There i s a d i f f e r e n c e by a f a c t o r of 18 between
t h e c o e f f i c i e n t s of thermal expansion o f copper and cuprous o x i d e f o r
i n s t a n c e /6/. Such a d i f f e r e n c e c a u s e s s t r e s s e s under t h e o x i d e isl a n d s wnen t h e sample i s c o o l e d down from 1173 K. P l a s t i c deformation
w i l l o c c u r t h e r e and c a u s e t h e Bordoni-peak. That n o t only s t r e s s e s
a r e r e s p o n s i b l e f o r t h e Bordoni-peak i s e v i d e n t , because a f t e r t h e
a n n e a l t h e samples were e t c h e d e l e c t r o l y t i c a l l y and a s u r f a c e l a y e r
i n c l u d i n g t h e o x y d e i s l a n d s was removed. For o x i d i z i n g a n n e a l s a t
1023 K t h e s u r f a c e o x i d a t i o n seems t o be reduced s o f a r , t h a t no
Bordoni-peak a p p e a r s (Fig. 3)
.
The a m p l i t u d e dependence o f sample 0.1023/3 (Fig.5) is much l e s s
pronounced t h a n t h a t of R.1023/2 ( F i g . 4 ) . T h i s cannot be due t o
d i f f e r e n c e s i n l o o p l e n g t h a l o n e , because f o r t h e reduced sample w i t h
t h e lower r e s i d u a l r e s i s t i v i t y r a t i o s h o r t e r l o o p l e n g t h s s h o u l d be
expected t h a n f o r t h e o x i d i z e d sample. Thus t h e r a t i o o f l o o p l e n g t h s
should be j u s t o p p o s i t e t o t h e observed behaviour of a m p l i t u d e dependence. T h e r e f o r e it i s assumed, t h a t d i f f e r e n t b i n d i n g e n e r g i e s
e x i s t between t h e p i n n i n g p o i n t s and d i s l o c a t i o n s f o r b o t h s t a t e s
of t h e samples. I n t h e reduced s t a t e one can e x p e c t a h i g h concent r a t i o n o f s i n g l e i m p u r i t y atoms a c c o r d i n g t o t h e low RRR-value.
The p i n n i n g p o i n t s t h a t determine t h e mean f r e e l o o p l e n g t h i n t h e
reduced samples w i l l be such s i n g l e i m p u r i t y atoms. I n accordance
w i t h t h e observed d i f f e r e n c e i n a m p l i t u d e dependence t h e i r b i n d i n g
energy should be s m a l l e r t h a n t h a t of t h e p i n n i n g p o i n t s i n t h e
o x i d i z e d s t a t e . I n t h i s s t a t e a l l o x i d i z a b l e i m p u r i t y atoms form
impurity-oxide c l u s t e r s , a s can b e seen from t h e h i g h e r RRR-value
of o x i d i z e d copper. One can e x p e c t t h a t impurity-oxides o r s m a l l
i m p u r i t y - o x i d e - c l u s t e r s w i l l a c t a s p i n n i n g p o i n t s i n t h e s e samples,
having a h i g h e r b i n d i n g energy a s t h e p i n n i n g p o i n t s i n t h e reduced
samples. Thus f o r t e m p e r a t u r e s up t o 323 K t h e i n t e r n a l f r i c t i o n of
sample 0.1023/3 i s amplitude-independent f o r a m p l i t u d e s 6 6x10-*.
V
-
SUMMARY
The i r r a d i a t i o n o f undeformed samples showed t h a t f o r t h e r e d u c e d
s t a t e t h e r e c r y s t a l l i z a t i o n t e m p e r a t u r e must b e d e c r e a s e d t o 1023 K
i n o r d e r t o o b t a i n p i n n i n g e f f e c t s a f t e r i r r a d i a t i o n . However, t h e n
t h e a m p l i t u d e dependence of i n t e r n a l f r i c t i o n b e g i n s a t a b o u t 1X I oW8
f o r 323 K. A l s o i n t h e o x i d i z e d s t a t e t h e a n n e a l i n g t e m p e r a t u r e h a s
t o b e d e c r e a s e d t o 1023 K t o a v o i d t h e e x i s t e n c e of a Bordoni-peak.
So b o t h t y p e s of s a m p l e s a r e s u i t a b l e f o r i r r a d i a t i o n e x p e r i m e n t s ,
b u t t h e r e d u c e d t y p e must b e measured a t v e r y low a m p l i t u d e s .
REFERENCES
/I/
E. T r o g e r , K. Liicke,G. S c h r o e d e r and G. Sokolowski; i n " I n t e r n a l F r i c t i o n a n d U l t r a s o n i c A t t e n u a t i o n i n S o l i d s " , Ed.
C.C. S m i t h , Pergamon P r e s s (1980) p.79
/ 2 / A. S c h n e l l , G.
8 (1980) 201
/3/
D.
K e e f e r , A.
/ 4 / B. Wantzen, G .
/5/
H.
/6/
R.F.
Sokolowski and K .
S o s i n ; A c t a Met.
11
Sokolowski a n d K .
Miillner; Nuovo Cirnento
33B
Liicke; C r y s t a l l L a t t i c e D e f e c t s
( 1 9 6 4 ) 1041
Liicke; t h i s c o n f e r e n c e
(1976) 177
T y l e c o t e ; J. I n s t . of M e t a l s
78
(1950/51) 7 8