DEFECT ANNEALING IN DILUTE Cu-ALLOYS AFTER IRRADIATION AND DEFORMATION

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DEFECT ANNEALING IN DILUTE Cu-ALLOYS AFTER IRRADIATION AND DEFORMATION

K. Tatsumi, H. Schmidt, D. Lenz, K. Lücke

To cite this version:

K. Tatsumi, H. Schmidt, D. Lenz, K. Lücke. DEFECT ANNEALING IN DILUTE Cu-ALLOYS AFTER IRRADIATION AND DEFORMATION. Journal de Physique Colloques, 1983, 44 (C9), pp.C9-723-C9-728. �10.1051/jphyscol:19839109�. �jpa-00223343�

JOURNAL DE PHYSIQUE

Colloque C9, suppl6ment a u n012, Tome 44, d k e m b r e 1983 page C9-723

DEFECT ANNEALING I N D I L U T E Cu-ALLOYS AFTER IRRADIATION AND DEFORMATION

K. Tatsumi, H. Schmidt, D. Lenz and K. Liicke

Institut ftir ATZgemeine MetaZZkunde und MetaZZPhysik, RWTH Aachen, F.R.G.

A b s t r a c t - S i n g l e c r y s t a l l i n e Cu and d i l u t e Cu-alloys ( w i t h S, Fe, Mn, Au, Be) were i s o c h r o n i c a l l y annealed (up t o 920 K) a f t e r i r r a d i a t i o n (3 MeV

-

s t r a h l u n g ) o r deformation (0.05<~<0.15% compression

1 1

I - INTRODUCTION

U l t r a s o n i c measurements of d i s l o c a t i o n resonance damping y i e l d i n f o r m a t i o n on t h e mean d i s l o c a t i o n l o o p l e n g t h L and d i s l o c a t i o n d e n s i t y h / l / . I n o r d e r t o g e t qood q u a n t i - t a t i v e data on d i s l o c a t i o n p i n n i n g (point d e f e c t annealing k i n e t i c s e. g. a f t e r i r r a - d i a t i o n ) s u i t a b l e values f o r A and Lo have t o be i n s t a l l e d by proper sample p r e p a r a t i o n i.e. deformation, a l l o y i n g and heat treatment. Measurements on d i l u t e a l l o y s a r e of s p e c i a l i n t e r e s t f o r s t u d i e s o f t h e i n t e r a c t i o n between f o r e i a n atoms (FA) and i r r a - d i a t i o n - i n d u c e d p o i n t - d e f e c t s (PD). Knowledge o f t h e FA/PD b i n d i n g energies i s impor- t a n t w i t h respect t o m a t e r i a l s behaviour e.g. under c o n d i t i o n s o f h i g h temperatures and/or i r r a d i a t i o n fluences. The present paper shows t h a t FA a d d i t i o n a l l y determine A and Lo i n a s p e c i f i c manner. This i s i n v e s t i g a t e d i n t h e present work by measure- ments o f L and A as f u n c t i o n o f annealing temperature TA a f t e r s l i g h t deformation a t

RT o f 5 d i l u t e Cu-alloys. The r e s u l t s a r e i n t e r p r e t e d by comparison w i t h t h e annealing behaviour o f pure copper b o t h a f t e r deformation and a f t e r y - i r r a d i a t i o n .

I 1 - EXPERIMENTAL

I n Tab.1 t h e d i f f e r e n t Cu-alloys a r e l i s t e d up (e.g. #Fe91 Cu+9latppmFe). The i n - f l u e n c e o f c o n c e n t r a t i o n o f t h e annealing i s r e p o r t e d elsewhere /2/. A l l samples

( I x l x l c m 3 ) were prepared by standard techniques /3/ (spark e r o s i o n c u t t i n g , g r i n d i n g , l a p p i n g ) from <I I I > - o r i e n t e d Bridgeman c r y s t a l s (1 1 x2x1 .5cm3 ). The f i n a l p l a n p a r a l l e - l i t y o f t h e a c o u s t i c endfaces was b e t t e r 5x10-5 cm/cm, t h e c r y s t a l o r i e n t a t i o n was w i t h i n 30' from t h e sound propagation d i r e c t i o n < I l l > . The a t t e n u a t i o n was measured a t RT w i t h MATEC-equipment (10

-

(RRR = 1000-2500). The d i l u t e a l l o y s were vacuum i n d u c t i o n smelted from ELMORE-Cu and 1% master a l l o y s . With a l l FA good s i n g l e c r y s t a l s were obtained i n t h e 10-500 ppm range except i n t h e case o f S where o n l y s t r i a t e d c r y s t a l s c o u l d be grown a t

c > 20 ppm. The S-, Mn-, and Au-crystals showed considerable m i c r o p o r o s i t y which was

detected u l t r a s o n i c a l l y and m e t a l l o g r a p h i c a l l y /4/. The f i n a l FA content was de- termined by t h e r e s i d u a l r e s i s t i v i t y o f t h e u l t r a s o n i c samples themselves (eddy c u r r e n t technique).

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19839109

JOURNAL DE PHYSIQUE

Tab. I

E I I

-

(i) Annealing a f t e r y - i r r a d i a t i o n o f pure Cu:

Fiq.l shows t h e a t t e n u a t i o n cx measured a t RT a t d i f f e r e n t frequencies f f o r t h e sample R1 (stan- dard p r e p a r a t i o n /3/: 0.1% predeformation + Zh,

923 K anneal) b e f o r e and a f t e r y - i r r a d i a t i o n (2400 yAh a t RT) and a f t e r isochronal annealing a t TA. The n o n - d i s l o c a t i o n background a t t e n u - a t i o n ag i s shown f o r comparison.

& shows t h e corresponding f-dependence o f d i s l o c a t i o n decrement 6 before i r r a d i a t i o n ( s o l i d c i r c l e s ) a f t e r i r r a d i a t i o n (0) and a f t e r annealing a t s e l e c t e d TA f i t t e d by KGL-master curves (exponential L - d i s t r i b u t i o n /2/). From fMAX(T ) t h e mean l o o p l e n g t h L ( T A )

is

l a t e d ? I / .

Fig.3 shows t h e TA-dependence L/L (Lo = l o o p l e n g t h i n t h e u n i r r a d i a t e d sample? and i r r a d i - a t i o n induce p i n n i n g p o i n t d e n s i t y An = L(TA!-I - Lo-?: d u r i n g i r r a d i a t i o n s t r o n g p i n n i n g takes p l a c e ( t h e corresponding pinning stage i s s i t u a t e d a t ² 260 K and a t t r i b u t e d t o s i n g l e vacancies, m i g r a t i o n energy UMv = 0.7 eV /5/). A second p i n n i n g stage i s observed a t 350-400 K and a t r r i b u t e d t o vacancies de- trapped from t r a c e i m p u r i t i e s ( e f f e c t i v e mi- g r a t i o n energy

UW

Annealing Temperature b rC1 p loo 200 MO WM

I C

--=-=---

# RllRRR=11001

Annealing Temperature TA lKI Fig. I

Frequency f [MHz1

Annealing Temperature T, rC1

2 0 100 2W 300 WM 500 600

b L

: ^:An -

La

9 ....

A

Anneating Temperature T* iK1

sample no change i n d i s l o c a t i o n d e n s i t y i s ob- served up t o t h e pre-annealing temperature 923 K.

The present r e s u l t s c o n f i r m e a r l i e r r e s u l t s by Inagaki e t a l . /6/.

( i i ) Annealing a f t e r deformation o f pure Cu:

Fig.4 shows a(TA) f o r sample R2 (annealed 6 d a t 1223 K a f t e r p r e p a r a t i o n ) b e f o r e ( E = 0%) and (0.5 h ) a f t e r deformation ( E = 0.04% compression a t RT). During these 30' a t RT t h e a t t e n u a t i o n decreases by about 20% which e f f e c t continues d u r i n g annealing up t o 480 K w i t h a w e l l d e f i n e d stage centered a t about 350 K (Stage E corres- ponding t o Stage I V o f p o i n t d e f e c t annealing).

I n Stage F (Fig.4) t h e a t t e n u a t i o n increases and f i n a l l y decreases i n Stage G.

Fig.5a-c show ~ ( f ) - d a t a f i t t e d by t h e KGL-master- curves. From Fig.5a i t i s seen t h a t Stage E i s caused by p i n n i n g and from Fig.5b t h a t Stage F i s caused by depinning o f d i s l o c a t i o n s w i t h no change o f A (up t o 676 K a l l s ( f )-curves have i d e n t i c a l HF-asymptotes). However, a t T > 676 K t h i s asymptote decreases i n d i c a t i n g a decrease o f A ( t h e annealing-out o f d i s l o c a t i o n s i s accompagnied by a minor L-increase, c f . s l i g h t decrease o f f M ~ X i n F i g . 5 ~ ) .

I

\ \I

I@\ 10 100 I\.. ₁₀₀₀ I

Frequency f LMHd

Fig.5b

Annealing Temperature 1,[*C1

0 100 200 3w w 540 600

Frequency [MHz] #R2IRRR=22001

-0-290 -n- 190 -0- 90 ~=0.04%

-0- 270 -v- 170

-.-

-0- 250 -*- 150 -a- 50

-1- 230 ^-s- 130 -0- 30

- -0-210 -'I10 -0- 10 A 5

2 -StogeE+StogeF+StageG-

I R .

3W LOO 5W 600 7W BW mi+

Annealing Temperature T.I K I

#RZ~RRR=22001

" .

0

Annealing Temperature

5 IKI

101 10 100 1000

Frequency f LMHzI

1*1 10 1W

Frequency f IMHd ¹⁰⁰⁰

F i g . 5 ~

Fig.6 shows L(TA) and h(TA) c a l c u l a t e d from _Anneal~ng Temperature T,PC1

Figs.5a-c. By comparison w i t h Fig.3 i t i s o IW 200 30 400 500 600 700

seen t h a t up t o 400 K y - i r r a d i a t i o n and de- -

f o r m a t i o n r e s u l t i n very s i m i l a r d i s l o c a t i o n p i n n i n g behaviour i n d i c a t i n g t h a t t h e same

g

pinners ( i .e. t h e same p i n n i n g k i n e t i c s ) a r e g4 involved. However, a f t e r deformation addi-

"

t i o n a l p i n n i n g takes p l a c e a t 400- 480 K

whereas a f t e r i r r a d i a t i o n depi nning i s already

g

measured a t T>440K. T h i s i n d i c a t e s t h a t FA-

t r a p p i n g o f vacancies has no i n f l u e n c e a t -

CI

T > 4 0 0 K i n pure Cu b u t t h a t i n t h e deformed sample t h e vacancies a r e " s e l f - t r a p p e d " i n

deformation induced vacancy agglomelates MO LOO 500 MK) 7w 8W 901

from which t h e y evaporate a t T > 4 0 0 K. Thus Annedmg Temperature Ta IK1

a t T > 450 K simultaneous p i n n i n g by such Fig. 6 vacancies

and

#R2IRRR=22001

5 \ ,&.-&

\

_\ -FkCP

o - - ~ ~ . /

-b 1

YoA-

"b

E=O \o\

--

. 4 % C ,.

&

-3 g

.-

2 1

1

C9-726 JOURNAL DE PHYSIQUE

o f s i n g l e pinners a t t h e d i s l o c a t i o n s takes place. Annealing Temperature T~ ~ C I

Both a f t e r i r r a d i a t i o n and a f t e r deformation t h e .O 100 ZOO 300 400 500 600 7%

depinning i s complete a t T

=

perature, however, a l r e a d y s i g n i f i c a n t changes o f A a r e observed a f t e r d e f o m a t i o n (Fig.6). I t i s known t h a t A-anneal i n g ( d i s l o c a t i o n recovery) i s a f u n c t i o n o f ^E and s t a r t s a t lower tempera- t u r e s w i t h i n c r e a s i n g E.

( i i i ) A n n e a l i n g a f t e r d e f o r m a t i o n o f d i l u t e c u - A1 l o y s :

F i q s . 7 a - e show a(TA) f o r t h e Cu-alloys i n Tab.1. 300 4 ~ ) 500 600 100 BOO 900

The a(T )-behaviour i s q u a n t i t a t i v e l y s i m i l a r t o Annealing Temperature E IKI

~ ( T A ) o f deformed pure Cu ( c f . Fig.4). The KGL

evaluated L(TA) and n(TA) behaviour i s shown i n F i g.7a Fig.8 and 9, resp.

Anneal~ng Temperature TA I'C1 Annealing Temperature T,I'C1

Annealing Temperature TA [KI Annealing Temperature h lK1

Fig. 7b F i q . 7 ~

Annealing Temperature TA I'C1 Annealing Temperature h rC1

.o loo

mo

# Hn2O # 5 5

~ o - ~ - O - ~ - o - . , - - "

300 400 500 600 700 800 900

Annealing Temperature & [KI Anneoling Temperature TA IK1

Fig.7d Fig. 7e

Annealing Temperature TA PC1

F i .8 shows t h a t t h e p i n n i n g stage E ( = Stage ^loo im 300 LOO 500 MIO m o

I V i s observed i n a l l a l l o y s w i t h t h e c e n t e r

-9-

An e s t i m a t e o f t h e FA/vacancy b i n d i n g energy UBV (see Tab.1) can be obtained by simply s c a l i n g TE w i t h t h e e f f e c t i v e m i g r a t i o n energy o.f t h e t r a c e i m p u r i t y determined 350 K p i n n i n g stage i n pure Cu ( ~ i = 1 . 0 5 eV = UMV+UBV = 0.7 eV + 0.35 ev, c f . ( i ) ) . Fig.8 shows (by comparison w i t h A ~ ( T ) a f t e r v - i + r a d i a t i o n ) t h a t i n t h e a l l o y s tfte Stage E p i n n i n g i n t e r - f e r e s w i t h d i s l o c a t i o n depinning a t T > 400 K.

Furthermore t h e FA/vacancy t r a p p i n g i s super- Annealing Temperature 5 [KT

imposed on t h e vacancy evaporation from de- Fig. 8

formation induced agglomerates ( c f . ( i i ) ) . The comparatively s t r o n g p i n n i n g i n Cu440Be and Cu5S a t temperatures where p i n n i n g by FA d e t r a p p i n g and/or evaporated va- cancies i n t e r f e r e s w i t h depinning by c l u s t e r i n g on t h e d i s l o c a t i o n s i s remarkable.

I n Cu440Be (Fig.7b) t h e p i n n i n g i s so s t r o n g t h a t t h e d i s l o c a t i o n s become almost completely pinned (which makes q u a n t i t a t i v e e v a l u a t i o n impossible a t T > 400 K.) To e x p l a i n t h i s we have t o assume t h a t Be-atoms are t r a n s p o r t e d t o d i s l o c a t i o n s by a vacancy- and/or mixed-dumbbell mechanism /7/. Even more remarkable i s t h e s t r o n g p i n n i n g i n Cu w i t h o n l y 5 ppm S. Here a l l p i n n i n g occurs r i g h t i n t h e f i r s t de- p i n n i n g range o f pure Cu (cf. Fig.3). Thus we conclude, t h a t i n Cu5S a l a r g e c o n t r i - b u t i o n t o t h e p i n n i n g i s caused by S-atoms t r a n s p o r t e d t o t h e d i s l o c a t i o n s by de- formation-induced vacancies. Fig.8 shows t h a t such a FA-transport a l s o i n f l u e n c e s p i n n i n g i n t h e o t h e r a l l o y s a t T 3 600 K and becomes predominant i n a l l a l l o y s a t T > 6 5 0 K: I n c o n t r a s t t o pure Cu where t h e depinning i n Stage F r e s u l t s i n complete unpinning (An = O), Stage F unpinning i n a l l o y s i s incomplete (An > 6 ) . Thus we con- clude t h a t t h e pinners which remain s t a b l e (e.g. a t 700 K) a r e n o t o f vacancy t y p e b u t a r e s o l u t e atoms; t h e i r number ~ n ( 7 5 0 K) i s given i n Tab.1. Since ~ n ( 7 0 0 K) i s expected t o be l a r g e r i n more concentrated a l l o y s a l s o t h e q u a n t i t y ~ n ( 7 0 0 K)/ci i s given i n Tab.1. The l a t t e r q u a n t i t y shows t h a t t h e s o l u t e t r a n s p o r t by deformation induced vacancies i s t h e more e f f e c t i v e t h e l a r g e r UBV i s .

With respect t o Stage G (T > 700 K) t h e a1 l o y s behave q u i t e d i f f e r e n t as compared w i t h pure copper: i n t h e a l l o y s f u r t h e r p i n n i n g occurs a t T where i n pure Cu a l l deforma- t i o n induced vacancy agglomerates a r e annealed o u t and depinning i s complete. Thus T > 700 K p i n n i n g i s due t o s o l u t e atoms which a r e t r a n s p o r t e d by thermal vacancies and segregate a t t h e d i s l o c a t i o n s according t o t h e i r d i s l o c a t i o n b i n d i n g energy UBD.

I n t h e case o f s h o r t range ( r - b) p i n n i n g f o r c e An.b=ci exp(UBD/kT). From ~ n ( 9 2 0 K) i n F i g.8 we o b t a i n t h e UBD-values given i n Tab.1. Such an e v a l u a t i o n o f U D i s j u s t i - f i e d o n l y i f ~ n ( 9 2 O K) r e f e r s t o thermal e q u i l i b r i u m . The f a c t t h a t An(iAY tends t o decrease a t v e r y h i g h temperatures (e.g. T > 850 K f o r Cu20Mn) i n d i c a t e s t h a t t h e

" C o t t r e l l cloud" evaporates already a t these temperatures and e q u i l i b r i u m i s a t t a i n e d . Fiq.9 shows t h a t t h e A-recovery i s s t r o n g l y Anneabng Temperature T~ I'CI

i n f l u e n c e d by t h e FA. Tab.1 gives t h e cha- o loo 200 300 400 500 wo 700

r a c t e r i s t i c temperatures TA d e f i n e d by

A / A o = 0.95 ( c f . Fig.9) T h i s temperature i s

expected t o be t h e h i g h e r t h e l a r g e r UBD i s because UBD determines t h e d i s l o c a t i o n mo- b i 1 i t y f o r t h e recovery processes (anni h i la - t i o n by c l i m b and/or g l i d e ) . The FA-segrega-

4

t i o n r e i n f o r c e s t h i s FA e f f e c t on d i s l o c a t i o n I

recovery. I t i s i n t e r e s t i n g t o note t h a t t h i s

g

s y n e r g i s t i c FA e f f e c t r e s u l t s i n a narrow

O ~ W 400 40 tm mo BOO 'XK) IW

A-annealing range (as compared w i t h pure Cu) Anneal~ng Temperahre E IKI

and t h a t TA i n Cu5S i s more than 300 K h i g h e r

than i n pure Cu, where recovery s t a r t s a t F i q. 9 400 K and continues up t o about 800 K.

I V

-

The i n t e r a c t i o n between f o r e i g n atoms (FA) and deformation-induced l a t t i c e defects (vacancies and d i s l o c a t i o n s ) determines t h e annealing behaviour o f d i l u t e Cu a l l o y s i n t h e T-range 290 - 920 K. The observed FA-effects r e f e r t o

( a ) t h e FA dependent p o s i t i o n o f the recovery stage I V , i n d i c a t i n g t h a t t h i s stage i s due t o annealing o u t o f vacancies a f t e r d e t r a p p i n g from FA.

(b) t h e FA t r a n s p o r t t o d i s l o c a t i o n s by deformation-induced vacancies.

( c ) t h e s o l u t e segregation a t d i s l o c a t i o n s under thermal equi 1 ib r i u m

( d ) t h e temperature above which d i s l o c a t i o n recovery occurs a f t e r deformation The present values f o r t h e FA/vacancy (UBV) and t h e F A / d i s l o c a t i o n (UBD) b i n d i n g energies i n Tab.1 a r e presumed t o be accurate by 2 0.1 eV, b u t t o represent c o r r e c t r e l a t i v e values o f t h e b i n d i n g energies f o r 5 i n t e r e s t i n g types o f FA i n Cu. The r e s u l t s f o r pure Cu and Cu91Fe i n d i c a t e t h a t (unknown) t r a c e i m p u r i t i e s ( i n t h e 1-5 ppm range) determine t h e p i n n i n g i n Stage I V i n these cases. T h i s shows t h a t t h e

C9-728 JOURNAL DE PHYSIQUE

Fe/vacancy binding energy must be smaller than 0.35 eV; possibly i t i s close t o zero as shown by recent MoRbauer s t u d i e s 181. The present investigation provides t h e proper annealing parameters f o r d i l u t e Cu alloys t o be used f o r point defect studies a f t e r i r r a d i a t i o n . The t r a c e impurity influence indicates t h a t improved UBV-data can be obtained by t h e present ultrasonic technique on 1 - 10 ppm alloys of a very high purity Cu-matrix (of s 0.1 ppm t o t a l impurities corresponding t o a residual r e s i s t i - v i t y r a t i o ² 10.000).

ACKNOWLEDGEMENTS

Work supported by t h e Deutsche Forschunqsgemeinschaft (SFB 125 Aachen-Julich-Koln) and t h e Minister f u r k'issenschaft und Forschung NRW (providing the Van-de-Graaff-

y - i rradiation f a c i l i t y ) . REFERENCES

/ I / D. Lenz, K., Lucke; "Proc. 5th ICIFUA" (D.Lenz, K-Liicke, ~ds.) Vol.11, p.48, Springer Berlin, Heidelberg, New York 1974

.

/2/ K. Tatsumi; Thesis RWTH Aachen, 1983.

/3/ P. Winterhager, K. Lucke; J. Appl. Phys. - 44 (1973) 4855.

/4/ H. Schmidt, D. Lenz, W. Uelhoff; t h i s conference /5/ P. Winterhager; Thesis RWTH Aachen, 1968

.

/6/ H. Inagaki, F. Hu)tgren, K. Lucke; Acta Met. 18 (1970) 713. -

/7/ A. Bartels, F. Dworschak, H.P. Meurer, C. Abromeit, H. Wollenberger;

J. Nucl. Mat. 83 (1979)

-