HAL Id: jpa-00221080
https://hal.archives-ouvertes.fr/jpa-00221080
Submitted on 1 Jan 1981
HAL is a multi-disciplinary open access
archive for the deposit and dissemination of
sci-entific research documents, whether they are
pub-lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d’enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.
A LOW TEMPERATURE COLD WORK
INTERNAL-FRICTION PEAK IN Al-0.5 Wt % Ga
Q. Kong, G. Li, T. Kê
To cite this version:
A LOW T E M P E R A T U R E C O L D W O R K I N T E R N A L - F R I C T I O N P E A K IN
A 1 - 0 . 5 Wt % GaQ.H. Kong, G.Y. L i and T . S . K6
I n s t i t u t e o f Metal Research (Shenyang) and I n s t i t u t e of Solid S t a t e Physics (Hefeil, Academia Sinica, China
A b s t r a c t . - An i n t e r n a l f r i c t i o n p e a k ; a r o u n d -84"C, f = 0 . 8 h p ) w a s o b s e r v e d i n A1-0.5 w t % ( 0 . 1 9 a t % ) G a c a l d - d r a w n t o 1 2 % r e d u c - t i o n i n a r e a a t 2 0 ' ~ . T h i s p e a k w a s s t a b l e when m e a s u r e m e n t s w e r e t a k e n b e l o w 20°C w i t h d e c e n d i n a a n d a s c e n d i n g t e m p e r a t u r e s a n d t h e h e i g h t o f t h e p e a k d e c r e a s e d a f t e r a n a n n e a l a t e l e v a t e d t e m - p e r a t u r e s . I t d i s a p p e a r e d c o m p l e t e l y a f t e r a n a n n e a l a t 2 0 0 " ~ . T h e p e a k h e i g h t f i r s t i n c r e a s e d a n d t h e n d e c r e a s e d w i t h t h e a m o u n t o f c o l d - w o r k i n g a t 2 0 ' ~ a a d a
12%
r e d u c t i o n i n a r e a s e e m s t o b e c l o s e t o t h e o p t i m u m a m o u n t o f c o l d - w o r k i n g . T h e a c t i v a t i o n e n t h a l p y a s s o c i a t e d w i t h t h i s i n t e r n a l f r i c t i o n p e a k m e a s u r e d w i t h t h e m e t h o d o f c h a n g i n g o f f r e q u e n c y i s 0 . 85 2 0 . 0 5 e V . A d i s - l o c a t i o n - k i n k d r a g g i n g m o d e l i s s s g g e s t e d i n w h i c h t h e m o b i l e a g e n t s t h a t i n t e r a c t w i t h d i s l o c a t i o n k i n k s a r e Ga a t o m - v a c a n c y p a i r s . T h e e f f e c t o f t h e t e m p e r a t u r e o f p r e v i o u s d e f o r m a t i o n o n t h e b e h a v i o r o f t h e i n t e r n a l f r i c t i o n p e a k i s d i s c u s s e d . I t i s c o n - t e m p l a t e d t h a t t h e b r o a d e n i n g o f t h e p e a k when t h e p r e v i o u s p l a s - t i c d e f o r m a t i o n w a s made a t -196OC may b e d u e t o t h e f o r m a t i o n o f Ga a t o m - d i v a c a n c y p a i r s . I . E x p e r i m e n t . - I n t e r n a l f r i c t i o n m e a s u r e m e n t s w e r e made w i t h a n i n v e r - t e d p e n d u l u m b y f r e e d e c a y m e t h o d . I n - s i t u t e n s i l e d e f o r m a t i o n w a s c a r - r i e d o u t b y an e l e c t r o m a g n e t i c s e t u p a n d t h e t e n s i l e f o r c e a p p l i e d t o t h e s p e c i m e n c a n b e r e g u l a t e d c o n t i n u o u s l y b y c h a n g i n g t h e m a g n i t u d e of t h e e l e c t r i c c u r r e n t p a s s i n g t h r o u g h a n i n d u c t i o n c o i l . T h e e l o n g a t i o n o f t h e s p e c i m e n w a s m e a s u r e d b y a r e a d i n g t e l e s c o p e . T h e A I - 0 . 5 w t % ( 0 . 19 a t %) G a s p e c i m e n s w e r e p r e p a r e d b y m e l - t i n g 9 9 . 9 9 9 a l u m i n u m a n d 9 9 . 9 9 Ga C p r o d u c e d i n C h i n a ) i n a v a c u u m i n - d u c t i o n f u r n a c e . T h e i n g o t o b t a i n e d w a s r o l l e d a n d d r a w n i n t o w i r e s . T h e f i n a l c o l d - w o r k i n g w a s made b y c o l d - d r a w i n g a r o d o f d i a m e t e r 2.6rnm t o 0 . 8 5 mm. T h i s c o r r e s p o n d s t o a c o l d - w o r k i n g o f 8 9 % r e d u c t i o n i n a r e a . T h e w i r e w a s a n n e a l e d a t 4 0 0 ' ~ f o r o n e h o u r a n d w a s u s e d a s t h e i n i t i a l s t a t e o f t h e s p e c i m e n . 2 . R e s u l t s.-
( a ) T e m p e r a t u r e i n t e r n a l - f r i c t i o n p e a k . An A I - 0 . 5 w t % GaC5-266 JOURNAL DE PHYSIQUE s p e c i m e n o f d i a m e t e r 0 . 8 4 m m w a s c o l d - d r a w n a t 2 0 ° C t o a d i a m e t e r o f 0 . 8 0 mm ( c o r r e s p o n d i n g t o
a
c o l d - w o r k i n g o f 1 2 % r e d u c t i o n i n a r e a ) a n d w a s t h e n m o u n t e d on t h e t o r s i o n p e n d u l u m . I n t e r n a l f r i c t i o n m e a s u r e - m e n t s w e r e t a k e n r e p e a t e d l y w i t h d e c e n d i n g a n d a s c e n d i n g t e m p e r a t u r e s a n d t h e Q - '-
T ( t e m p e r a t u r e ) c u r v e o b t a i n e d i s shown i n F i g . l. A p e a k a p p e a r e d a t -8 4-C w i t h f = 0 . 8 Hz. T h e h e i g h t o f t h e p e a k w a s a b o u t I I O - ~ . C'.l0' n4 AI-OSwt%m 32 -30 After 12% Extnrson at ZO'C
20 Aftat IW'C x 3Omln A n d i q
2.6 After 150t* 3 0 m ~ n A*Wr%
24 0 After mtx 3Omin Anreling
22 2 0 18 1.6 - 14 - 12 10 .8 6 4
-
1 F i g . 1 . Q -T c u r v e o f A 1 0 . 5-
F i g . 2 . E f f e c t o f a n n e a l i n g w t % Ga d e f o r m e d 1 2 % r e d u c --
t e m p e r a t u r e o n t h e - 8 4 ' ~ t i o n i n a r e a a t 2 0 ° c ( f = 0 . 8Bz).
i n t e r n a l f r i c t i o n p e a k . T h e i n t e r n a l f r i c t i o n of t h e a b o v e s p e c i m e n w a s m e a s u r e d a f t e r a n a n n e a l o f ha3.f a n h o u r a t s u c c e s s i v e l y h i g h e r t e m p e r a t u r e s a n d t h e c u r - v e s o b t a i n e d a r e shown o n F i g . 2 . I t i s s e e n t h a t t h e p e a k t e m p e r a t u r e d i d n o t c h a n g e n o t i c e a b l y a f t e r t h e s p e c i m e n h a d b e e n a n n e a l e d a t d i f - f e r e n t t e m p e r a t u r e s o n l y t h a t t h e h e i g h t o f t h e p e a k d e c r e a s e d s u c c e s - s i v e l y a n d d i s a p p e a r e d c o m p l e t e l y a f t e r a n a n n e a l a t 2 0 0 D C . T h e e f f e c t o f t h e a m o u n t o f c o l d - w o r k i n g a t r o o m t e m p e r a t u r e ( 5 , 1 2 a n d 3 6 % e x t e n s i o n ) on t h e t e m p e r a t u r e i n t e r n a l f r i c t i o n p e a k a t -84'C ( f = 0 . 8 Hz) i s s h o w n i n F i g . 3 . An o p t i m u m a m o u n t o f c o l d - w o r k i n g s e e m s t o b e 1 2 % e x t e n s i o n . %L. AI -0Swt2.G~ 3.230 *After l2% Extruvon ~ R a o m Temp
a ' A f t " 36% Extrur#on m! Rwm Temp.
C5-268 JOURNAL DE PHYSIQUE
internal friction measurements were taken with ascending temperatures.
3. ~ i s c u s s i o n s . - I n 1949, internal friction peak (as a function of
temperature of measurement) has been observed i n cold-worked AI-0.5 %
Cu with peak temperature in the range of 25OC to 5 0 ' ~ (f I 1 HZ). (1,2)
I n 1979, two temperature internal friction peakswere observed i n cold-
worked AI-0.03 wt % Mg around 60°c and - 3 0 " ~ . (3). The higher tempera-
ture peak has been attributed to the interaction of Mg atoms with dis- locations in aluminum similar to the peak previously observed i n
AI-0.5 % Cu specimens. A dislocation-kink atmosphere-dragging model has
been suggested for the relaxation mechanism of these peaks (4,2,5). The
lower temperature peak i n cold-worked AI-0.03 % Mg has been attributed
to the interaction of Mg atom-vacancy pairs with dislocations in alu- minum (3). We think that the lower-temperature internal-friction peak
observed in AI-0.5 % G a around -84-C may also be attributed to the in-
teraction of Ga atom-vacancy pairs with dislocations i n aluminum. Similar low-temperature peaks have been observed in cold-worked
dilute aluminum alloys (6) as well as i n cold-worked dilute copper
alloys
(7).
Such low-temperature peaks are different from the Hasigutipeaks which are suppressed by the presence of solute atoms. The models proposed so far for such low-temperature peaks seem to be all based on the thermal depinning of dislocations. A possible reason for the prefe- rence of such an immobile-solute atom model may be due to the conside- ration that the migration rate of substitutional solute atoms in the lattice is too slow at such a low temperature at which the relaxation process was observed.
Now let us focus our attention to dilute aluminum alloys in which the dislocations are not extended. In proposing a dislocation-kink atmo- phere-dragging model for the explanation of the internal friction peaks
exhibiting an anomalous amplitude effect of AI-0.5 % Cu and AI-0.1
X
Mg,we have emphasized the point that in order that the substitutional solu- te atom atmosphere can be dragged to move along with the dislocation, the solute atoms constituting the atmosphere must have a diffusion coef- ficient about ten orders of magnitude larger than the usual value. T h e
argument is as follows : (4,2) The average distance X that a diffusing
particle having a diffusion coefficient D can migrate in time
T is X g (DT) 112. Consider the case of the Q-1 peak observed in
AI-0.5% Ga (-84OC, f 0 . 8 HZ). We have T U 2 1 at the peak temperature
1 5 3 K , where w is the angular frequency, so that T l/w = 1 / 2 n f = 0.2
sec. Assuming the atmosphere be dragged along to move an average dis-
tance of b (~urger's vector) in time r during.the Q-i measurements, e.g.,
-
8JOURNAL DE PHYSIQUE
REFERENCES
( 1 ) T . S . K B , P h y s . R e v . , 78 ( 1 9 5 0 ) 4 2 0 .
( 2 ) T. S . K;, i n " ~ 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 " ( e d i t o r : C . C . S m i t h , P e r g a m a n P r e s s , O c t . 1 9 8 O ) , p . 1 5 7 . ( 3 ) Z . L . P a n , Z . G . Wang, Q . H . Kong a n d T.S.
