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DISLOCATION MOTION IN VA METALS STUDIED BY INTERNAL FRICTION
S. Okuda, H. Mizubayashi, N. Kuramochi, S. Amano, M. Shimada, H.
Tatekawa
To cite this version:
S. Okuda, H. Mizubayashi, N. Kuramochi, S. Amano, M. Shimada, et al.. DISLOCATION MOTION
IN VA METALS STUDIED BY INTERNAL FRICTION. Journal de Physique Colloques, 1981, 42
(C5), pp.C5-67-C5-72. �10.1051/jphyscol:1981509�. �jpa-00220966�
JOURNAL DE PHYSIQUE
CoZZoque C5, suppZ6ment au nO1O, Tome 42, octobre 1981 page C5-67
DISLOCATION MOTION IN V A METALS STUDIED BY INTERNAL FRICTION
S. Okuda, H. Mizubayashi, N. Kuramochi, S. Amano, M. Shimada and H. Tatekawa I n s t i t u t e of Materiazs Science, University of Tsukuba, S a k m a - m a ,
Ibaraki 305, Japan
A b s t r a c t . - D i s l o c a t i o n motion i n Va m e t a l s , V , Nb and Ta a t low t e m p e r a t u r e s was s t u d i e d by i n t e r n a l f r i c t i o n and dynamic modulus measurements. The
r e s u l t s on p u r e and impure Nb and Ta support t h e assignment t h a t t h e 6 and a peaks a r e i n t r i n s i c d i s l o c a t i o n r e l a x a t i o n peak and H c o l d work peak,
r e s p e c t i v e l y .
D i s l o c a t i o n motion below t h e 6 peak t e m p e r a t u r e s a t s a y 9K was d i s c u s s e d based on t h e observed e f f e c t of deformation and E charge on modulus d e f e c t s a t 9K. Modulus d e f e c t s a t 9K were considered t o be mainly due t o k i n k d i f f u s i o n along screw and non-screw d i s l o c a t i o n s and t h e 6 peak was consid- e r e d t o be a s s o c i a t e d w i t h double k i n k formation on non-screw d i s l o c a t i o n s . H charge suppressed t h e modulus d e f e c t s a t 9K and seemed t o induce a very s t r o n g d i s l o c a t i o n pinning which i s s t a b l e up t o room temperature.
Other t y p e s of d i s l o c a t i o n pinning observed i n V a f t e r quenching t h e specimen deformed and H charged were a l s o shown.
1. I n t r o d u c t i o n . - Many works have now been accumulated on d i s l o c a t i o n r e l a x a t i o n peaks i n group-Va m e t a l s , V , Nb and Ta. These r e l a x a t i o n peaks a r e t y p i c a l l y from low t e m p e r a t u r e s , t h e 6, a,
B
m d y peaks which appear roughly a t around 30K(6), 150K(a), 300K(B) and 500K(y) f o r measuring frequency of 500Hz(l%3). There seems t o b e a g e n e r a l agreement on t h a t t h e y peak i s caused by t h e double kink formation on screw d i s l o c a t i o n s and t h e B peak, by p o i n t d e f e c t ( o t h e r t h a n H ) - d i s l o c a t i o n i n t e r - a c t i o n ( 4 ) . On t h e o r i g i n s of t h e 6 and a peaks, however, t h e r e a r e s t i l l controver- s i e s among v a r i o u s a u t h o r s . Main p o i n t i s whether t h e a peak is a hydrogen cold- work peak(HCWP) o r an i n t r i n s i c d i s l o c a t i o n r e l a x a t i o n peak(1DRP).The experimental r e s u l t s t h a t t h e 6 peak i s suppressed by H charge b u t t h e a peak appears only a f t e r H c h a r g e ( 2 , 3 ) and t h a t r e l a x a t i o n s t r e n g t h s o r modulus d e f e c t s accompanying t h e 6 peak(AE6) and t h e a peak(AE ) a r e i n complementary
a
r e l a t i o n , i . e . AE +AE I c o n s t . (5,6) a r e i n f a v o r of t h e former model. However, K l a m
6 a
e t a1.(7) and S c h u l t z e t a 1 . ( 8 ) have observed r e c e n t l y t h a t i n c a r e f u l l y prepared Nb and Ta specimens t h e a peak appeared i n t h e deformed specimen without H charge and concluded t h a t t h e a peak i s IDRP. I n t h e p r e s e n t p a p e r , t h e e x p e r i m e n t a l r e s u l t s w i l l be shown which s u g g e s t t h a t t h e 6 and a peaks a r e IDRP and HCWP, r e s p e c t i v e l y .
I n o r d e r t o c l a r i f y t h e d i s l o c a t i o n motion, it i s i m p o r t a n t t o know t h e d i s l o - c a t i o n behavior below t h e 6 peak temperatures. I n t h i s r e s p e c t , changes i n modulus d e f e c t s below t h e 6 peak caused by deformation, H charge and quenching were s t u d i e d
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1981509
C5-68 JOURNAL DE PHYSIQUE
i n t h e p r e s e n t work.
2. E x p e r i m e n t a l . - Specimens used i n t h e p r e s e n t work were s i n g l e c r y s t a l ( S C ) s p e c i - mens of V and Nb and p o l y c r y s t a l ( P C ) specimens of Nb and Ta, a l l purchased from MRC.
They were a n n e a l e d i n UHV i n t h e r a n g e of 1 0 - ' % 1 0 - ~ ~ a . The t y p i c a l 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 were r o u g h l y about 25 f o r b o t h V and Nb SC-specimens, and about 2500 f o r Nb and Ta PC-specimens. Deformation of t h e specimens was made by bending o r r o l l i n g . H c h a r g e was performed c a t h o d i c a l l y a t O°C. I n t e r n a l f r i c t i o n and dynamic modulus were measured d u r i n g warmup u s i n g f l e x u r a l v i b r a t i o n of about 500Hz. Maximum s t r a i n a m p l i t u d e was a n o r d e r of 1 0 -6
.
- 0-
QJ
TR POLY. -H PO34440
TEMPERATURE [Kl
F i g . l ( a )
F i g s . l ( a ) and (b) : I n t e r n a l f r i c t i o n and dynamic modulus of Ta p o l y c r y s t a l specimens.
( a ) : A specimen was deformed by r o l l i n g (45% r e d u c t i o n )
( c u r v e s l ) , and t h e n H charged by 550atppm(curved 2 ) . RRR=
2300. Measuring f r e q u e n c y = 230Hz. Curve 3 ; f o r a n o t h e r specimen as-annealed b u t w i t h a h a n d l i n g e f f e c t . RRR=5000.
Measuring frequency=850Hz.
( b ) : For low p u r i t y specimens.
Curve 1 ; f o r a specimen a n n e a l e d and deformed 4.8% by bending (RRR=18). Curve 2 ; f o r a specimen a s - r e c e i v e d , p r o b a b l y contaminated by H
(RRR=50). Measuring f r e q u e n c y -180Hz.
TENPERRTURE [KI
F i g . l ( b )
3. E f f e c t of p u r i t y on t h e 6 and a peaks.- F i g u r e s l ( a ) and (b) show t h e r e s u l t s on p u r e and impure Ta. I n F i g . l ( a ) , heavy d e f o r m a t i o n induced o n l y t h e 6 peak(%35K) ( c u r v e I ) , and H c h a r g e s u p p r e s s e d t h e 6 peak and induced t h e a p e a k ( c u r v e 2 , al a t
%150K, a2 a t %200K). F u r t h e r , modulus changes accompanying w i t h t h e s e peaks show t h a t AE +AE = c o n s t . ( s e e u p p e r c u r v e s 1 and 2 ) . I n t h e as-annealed specimen, t h e
6 a
s m a l l 6 , a (%80K) and a peaks a p p e a r e d p r o b a b l y d u e t o h a n d l i n g e f f e c t ( c u r v e 3 ) .
3 1
I n F i g . l ( b ) , s i m i l a r r e s u l t s on impure specimens a r e shown. Here, t h e a s - r e c e i v e d specimen r e p r e s e n t s a deformed specimen c o n t a i n i n g H.
R e s u l t s on p u r e and impure Nb's a r e compared i n Fig. 2. They a r e s i m i l a r t o t h o s e on Ta, b u t i n p u r e Nb, even t h e specimen c a r e f u l l y p r e p a r e d n o t t o a b s o r b H and o n l y deformed showed t h e l a r g e a peak(upper f i g u r e ) . From t h e s e r e s u l t s on Nb and Ta, i t seems more r e a s o n a b l e t o c o n s i d e r t h a t a v e r y s m a l l amount of H remaining i n p u r e specimens was r e s p o n s i b l e t o t h e a peak i n Nb t h a n t o c o n s i d e r t h a t t h e a peak i n Nb i s IDRP. It seems t h a t i n impure specimens i n i t i a l l y c o n t a i n e d H atoms were t r a p p e d by i m p u r i t i e s and could n o t c o n t r i b u t e t o HCWP. T h e r e f o r e , t h e 6 and a peaks a r e c o n s i d e r e d t o b e IDRP and HCWP, r e s p e c t i v e l y .
3. D i s l o c a t i o n motion below t h e 6 peak t e m p e r a t u r e s . - The 6 peak i s now IDRP, t h e n what t y p e of d i s l o c a t i o n motion i s r e s p o n s i b l e f o r t h e modulus d e f e c t s below t h e 6 peak t e m p e r a t u r e s ? F i g u r e s 3 ( a ) and (b) show t h e e f f e c t of d e f o r m a t i o n and H c h a r g e on t h e modulus d e f e c t s a t ~K((L!E/E~)~~) f o r Nb SC-specimens. (AE/E0)9;c i n c r e a s e d a f t e r s u c c e s s i v e d e f o r m a t i o n s and d e c r e a s e d by f o l l w i n g H c h a r g e s .
F o r an as-annealed specimen, 220atppm H c h a r g e was observed t o d e c r e a s e t h e modulus a t 9K by about 0.9% o r t o i n c r e a s e (AE/E ) by about 0 . 9 % ( n o t shoxm h e r e ) .
0 9K
T h e r e f o r e , t h e above changes i n (AE/E0)9K were c o n s i d e r e d t o b e mainly a s s o c i a t e d
N I O B I U M
1251 I I I I I
F i g . 2 : I n t e r n a l f r i c t i o n of Nb poly- c r y s t a l s p e c i m e n s ( h i g h p u r i t y , upper f i g u r e ) and a s i n g l e c r y s t a l specimen
(low p u r i t y , lower f i g u r e ) w i t h v a r i o u s t r e a t m e n t s . H e r e , O2 t r e a t m e n t means a n o x i d e f i l m f o r m a t i o n d u r i n g c o o l i n g i n UHV i n o r d e r t o p r e v e n t H a b s o r p t i o n i n t o a specimen.
T E M P E R A T U R E ( K )
JOURNAL DE PHYSIQUE
- 3
~~~
0 DEFORMATION ( ' I . ) 2 4 6 8 10 .J0 p p m ~1 :l
.1100 PpmH
Fig. 3 ( a ) Fig. 3(b)
F i g s . 3 ( a ) and
(M
: (a) : E f f e c t of deformation and H charge on dynamic modulus a t 9K(solid l i n e ) and t h e i r d e r i v a t i v e ( b r o k e n l i n e ) i n a Nb s i n g l e c r y s t a l specimen. Successive deformations were made by bending a t room temperature. (b) : S i m i l a r t o ( a ) b u t deformations were made a t 77K.w i t h an i n c r e a s e i n mobile d i s l o c a t i o n d e n s i t y a f t e r deformations and w i t h a suppres- s i o n of d i s l o c a t i o n motion a f t e r H charges. F i g u r e s 3 ( a ) and (b) f u r t h e r show t h a t
(AE/EOIgK is l a r g e r a f t e r deformation a t 77K than a f t e r deformation a t room tempera- t u r e . On t h e o t h e r hand, t h e 6 peak i s l a r g e r a f t e r deformation at room tempera- t u r e . Since t h e lower temperature deformation i s considered t o induce more long screw d i s l o c a t i o n s , t h e s e r e s u l t s suggest t h a t t h e 6 peak i s a s s o c i a t e d w i t h double k i n k formation on non-screw d i s l o c a t i o n s and (AE/E0)9K i s due t o kink d i f f u s i o n along screw and non-screw d i s l o c a t i o n s .
I n t h e s e c o n s i d e r a t i o n s , a c o n t r i b u t i o n of d i s l o c a t i o n motion i n t h e i n t e r n a l s t r e s s f i e l d t o (AE/E0)9K should be t a k e n i n t o account. But, observed l i t t l e amplitude dependence of AEgK seems t o support t h e g e n e r a l f i g u r e mentioned above.
Now r e t u r n e d t o t h e r e s u l t s on Ta shown i n Fig. l ( a ) , c u r v e s 1 and 2 of t h e modulus change show t h a t ( A E / E ~ ) ~ ~ i n Ta decreased by H charge and t h i s decreased component was n o t r e l e a s e d a t l e a s t up t o room temperature. This r e s u l t s u g g e s t s t h a t motion of d i s l o c a t i o n k i n k s was suppressed up t o room temperature. Such a s t r o n g pinning of d i s l o c a t i o n s by H seems t o b e d i f f i c u l t t o e x p l a i n a t p r e s e n t , b u t s t a b l e H c l u s t e r s on d i s l o c a t i o n k i n k s might b e a p o s s i b l e o r i g i n .
There a r e o t h e r t y p e s of d i s l o c a t i o n pinning which were observed i n deformed V.
F i g u r e 4 shows t h e e f f e c t of c o o l i n g r a t e on modulus d e f e c t s . On curve 3 i n t h e f i g u r e f o r quenched specimen, d i s l o c a t i o n pinning by H atoms can be seen a t about
Fig. 4 : E f f e c t of c o o l i n g r a t e on low t e m p e r a t u r e dynamic modulus i n a V s i n g l e c r y s t a l specimen a f t e r d e f o r m a t i o n and H c h a r g e . Changes i n v i b r a t i o n a l p e r i o d of r e s o n a n t f l e x u r a l v i b r a t i o n a f t e r v a r i o u s t r e a t m e n t s ( P X ) , t a k e n a s d i f f e r e n c e from t h a t i n t h e as-annealed
s t a t e ( P R ) were p l o t t e d a g a i n s t measuring t e m p e r a t u r e s . The measurements were made d u r i n g warmup a f t e r t h e f o l l o w i n g s u c c e s s i v e t r e a t m e n t s .
1 : Deformed by bending(22%) a t room t e m p e r a t u r e . 2 : 30atppm H charged.
3%6 : A t o t a l of 175atppm H charged and cooled by t h e f o l l o w i n g ways.
3 : Quenched from room t e m p e r a t u r e i n t o l i q u i d He. A 1st warmup t u n t o 60K(lower c u r v e ) c o i n s i d e s a t %25K w i t h a 2nd r u n , showing d i s l o c a t i o n p i n n i n g .
4 : Cooled by o r d i n a r y r a t e from room t e m p e r a t u r e t o 5K i n a few h o u r s . 5 : Slowly c o o l e d i n 1 day.
6 : Quenched and a n n e a l e d a t about 170K, and t h e n v e r y s l o w l y cooled t o 5K t a k i n g about 1 day.
25K, which c o r r e s p o n d s p r o b a b l y t o t h e H d e t r a p p i n g s t a g e found by e l e c t r i c a l r e s i s - t i v i t y measurements(9). L a r g e d i s l o c a t i o n p i n n i n g and d e p i n n i n g s t a g e s o b s e r v e d i n t h e r a n g e from 120K t o 180K i s p r o b a b l y a s s o c i a t e d w i t h c l u s t e r i n g and r e s o l u t i o n of H atoms on o r n e a r d i s l o c a t i o n l i n e s , H atoms h a v i n g been d e t r a p p e d from i m p u r i t i e s d u r i n g warmup. Some of t h e d e t a i l e d r e s u l t s w i l l b e p u b l i s h e d e l s e w h e r e ( l 0 ) .
R e f e r e n c e s
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103(1969).3. G. C a n n e l l i and F.M. Mazzolai, J Phys. Chem. S o l i d s ,
1,
1913(1970).4. A. Segger and C . ~ G t h r i c h , Nuovo Cimento,
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38(1976).5. H. Mizubayashi, S. Okuda and M. Daikubara, S c r i p t a Met.,
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1131(1979),H. Mizubayashi, M. Daikubara and S. Okuda, P r o c . 2nd JIMIS-2, Hydrogen i n M e t a l s , Suppl. Trans. J I M ,
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7. R. Klam, H. S c h u l t z and H.-E. S c h a e f e r , A c t a Met.,
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205(1979).8. H. S c h u l t z , U. R o d r i a n and M. Maul, P r o c . 3rd European Conf., I n t e r n a l F r i c t i o n and 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 , Pergamon P r e s s , London, p.19(1980).
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955(1974).10. N. Kuramochi, H. Mizubayashi and S. Okuda, t o b e p u b l i s h e d .
