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ON THE INTERACTION BETWEEN 57Co ATOMS AND THE QUENCHED-IN VACANCIES IN
ALUMINIUM
K. Sassa, H. Goto, Y. Ishida
To cite this version:
K. Sassa, H. Goto, Y. Ishida. ON THE INTERACTION BETWEEN 57Co ATOMS AND THE
QUENCHED-IN VACANCIES IN ALUMINIUM. Journal de Physique Colloques, 1979, 40 (C2),
pp.C2-559-C2-560. �10.1051/jphyscol:19792194�. �jpa-00218572�
JOURNAL DE PHYSIQUE
Colloque
C2,suppl6ment au n
O3, Tome 40, mars
1979,page
C2-559ON THE I N T E R A C T I O N BETWEEN 5 7 C o ATOMS AND THE QUENCHED-IN VACANCIES I N A L U M I N I U M
K. S a s s a , H. Goto and Y . I s h i d a
I n s t i t u t e o f I n d u s t r i a l Science, U n i v e r s i t y o f Tokyo,
7Roppongi, Minato, Tokyo, Japan
R 6 s u d . - Des f e u i l l e s d'aluminium d o p e e s a u 5 7 ~ o o n t C t C rapidement trempCes d e p u i s l e s h a u t e s tem- p 6 r a t u r e s . Dans l e s p e c t r e Mgssbauer, un nouveau p i c a p p a r a P t 2 0 , 2 4 mm/s, c e q u i e s t p l u s f a i b l e e n B n e r g i e que c e l u i d e l a s o l u t i o n s o l i d e ( 0 . 3 3 mm/s). C e c i s u g g i r e l ' e x i s t e n c e d ' i n t e r a c t i o n s c o b a l t - l a c u n e . L ' i n t e n s i t C r e l a t i v e du p i c dspend d e l a t e m p e r a t u r e d e t r e m p e , m a i s p a s de s a p o s i - t i o n q u i e s t l a mdme que c e l l e o b s e r v g e a v e c un a l l i a g e A1-0.02 a t % 5 7 ~ e . L e s t e m p e r a t u r e s d e Debye c o r r e s p o n d a n t a u p i c d e s o l u t i o n s o l i d e e t a u p i c de l a c u n e s o n t 235 K e t 300 K r e s p e c t i v e m e n t A b s t r a c t . - 5 7 ~ o - d o p e d aluminium f o i l specimen was r a p i d l y quenched from h i g h t e m p e r a t u r e s . I n t h e
~ g s s b a u e r s p e c t r u m , a new peak a p p e a r e d a t 0.24 mm/s which i s lower i n t h e e n e r g y l e v e l by 0 . 3 3 m/s t h a n t h e s o l i d s o l u t i o n p e a k , s u g g e s t i n g t h e i n t e r a c t i o n o f "CO w i t h t h e v a c a n c i e s . The l i n e a r e a depended o n t h e q u e n c h i n g t e m p e r a t u r e , b u t n o t t h e p o s i t i o n . The l i n e p o s i t i o n was t h e same a s t h a t o f A1-0.02 a t % 5 7 ~ e a l l o y . The Debye t e m p e r a t u r e s were 235 K and 300 K f o r t h e s o l i d s o l u t i o n peak and t h e vacancy p e a k , r e s p e c t i v e l y .
I . I n t r o d u c t i o n . - ~ z s s b a u e r s p e c t r o s c o p y i s a unique
t o o l t o o b s e r v e t h e i n t e r a c t i o n between G s s b a u e r i m p u r i t y atoms and l a t t i c e d e f e c t s . I t e n a b l e s u s t o d e t e c t changes i n t h e e l e c t r o n i c and l a t t i c e dynami- c a l p r o p e r t i e s o f t h e i m p u r i t y atoms a s s o c i a t e d w i t h t h e d e f e c t s a s w e l l a s t h e k i n e t i c s o f t h e r e a c t i o n s
111.
A f t e r a v e r y r a p i d q u e n c h i n g o f a n A1-0.02 a t % 5 7 ~ e a l l o y , H . I c h i n o s e e t a l . / 2 / , / 3 / found a new peak which i s l i k e l y t o be t h a t o f 5 7 ~ e a s s o c i a - t e d w i t h t h e v a c a n c i e s . The s m a l l n e s s o f t h e p e a k , however, p r o h i b i t e d f u r t h e r a n a l y s i s .
Miissbauer s o u r c e e x p e r i m e n t u s i n g 5 7 ~ o was performed s i n c e t h e c o n c e n t r a t i o n o f Miissbauer atoms c a n b e lowered t o l e s s t h a n lo-' which i s two o r d e r s o f magnitude l o w e r t h a n t h a t o f quenched-in vacan- c i e s . The same peak was o b t a i n e d / 4 / when a 5 7 ~ o - doped aluminium t h i n f o i l was quenched, and more p r e c i s e a n a l y s i s on t h e n a t u r e o f t h e new peak beca- me f e a s i b l e .
I n t h i s p a p e r , t h e e f f e c t s o f vacancy concen- t r a t i o n t o t h e Fe-vacancy s t r u c t u r e and t h e l a t t i c e dynamical p r o p e r t i e s o f t h e complex were examined.
2 . Experimenta1s.- The specimen i s a 99.999 % a l u - minium f o i l (15 x 15 mm 100 pm) i n which a b o u t 2 MBq o f c a r r i e r f r e d 5 7 ~ o was doped. The r a p i d q u e n c h i n g was performed i n a v e r t i c a l f u r n a c e w i t h d r y a r g o n
mode. The s p e c t r u m i s c o n n e c t e d w i t h r e s p e c t t o t h a t o f a - i r o n a t room t e m p e r a t u r e .
3. R e s u l t s and d i s c u s s i o n . - F i g u r e I ( a ) shows t h e s p e c t r u m o f t h e specimen quenched from 8 7 3 K. A new peak a p p e a r e d a t 0.24 mm/s which i s lower i n t h e e n e r g y l e v e l by 0 . 3 3 mm/s t h a n t h a t o f s o l i d s o l u - t i o n 5 7 ~ e . F i g u r e I ( b ) i s t h e s p e c t r u m o f t h e same specimen aged a t 233 K f o r 10 min.
a t m o s p h e r e by d r o p p i n g t h e specimen i n t o CaC12.6H20
s o l u t i o n k e p t a t 233 K. A f t e r q u e n c h i n g , t h e s p e c i - F i g . 1 : MGssbauer s p e c t r u m o f 5 7 ~ o - d o p e d aluminium specimen ( a ) quenched from 8 7 3 K , ( b ) quenched and men was p l a c e d i n a l i q u i d n i t r o g e n c r y o s t a t e q u i p - aged a t 233
for
10 min., ( c ) from 8 1 3 K ped w i t h a h e a t i n g u n i t . For t h e MEssbauer measure- and ( d ) quenched and aged a t 241 K f o r 10 min. Then e g a t i v e v e l o c i t y means t h a t t h e r e s o n a n c e e n e r g y m n t , t h e a b s o r b e r o f NasFe (CN)6.10H20 c o n t a i n i n g l e v e l o f t h e s o u r c e specimen i s l o w e r t h a n t h a t o f
1 g 5 7 ~ e / m 2 was v i b r a t e d i n c o n s t a n t a c c e l e r a t i o n t h e s t a n d a r d a b s o r b e r .
37
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792194
C2-560 JOURNAL DE The area o f t h e new peak i n c r e a s e d t o 75 % o f t h e
PHYSIQUE
t o t a l a b s o r p t i o n . Figure I ( c ) i s t h e spectrum o f t h e same specimen quenched from 813 K , and f i g u r e l ( d ) i s t h a t measured a f t e r ageing t h e specimen i n t h e same way. The area i n c r e a s e d t o 50 % o f t h e t o - t a l a b s o r p t i o n . The peak r e t a i n e d t h e same parame- t e r s c o n s t a n t up t o t h e ageing t r e a t m e n t a t 313 K f o r 10 min. I t decayed a f t e r t h e ageing a t h i g h e r t e m p e r a t u r e s . At t h e same time t h e p o s i t i o n and t h e l i n e w i d t h changed. Such an ageing b e h a v i o r was t h e same a s w i t h t h e quenching from 873 K 141. In t h e specimen quenched from 663 K , t h e peak was undetec- t a b l e . The r e d u c t i o n i n t h e a r e a o f the new peak occurred w i t h t h e r e d u c t i o n o f t h e quenching tempe- r a t u r e . The b e h a v i o r s u p p o r t s t h e v i e w t h a t t h e peak i s d u e t o 5 7 ~ o / 5 7 ~ e atoms i n t e r a c t e d w i t h t h e quen-
ched-in v a c a n c i e s .
The p o s i t i o n s o f t h e new peaks i n f i g u r e 1 were t h e same a s t h a t o f an A1-0.02 at%Fe a l l o y ; t h e isomer s h i f t o f t h e new peak does n o t change i r r e s p e c t i v e o f t h e r a t i o between t h e number o f im- p u r i t y atoms and v a c a n c i e s . I t i s thought t h a t t h e s i t e o f 5 7 ~ o / 5 7 ~ e atoms i n t h e complex w i t h vacan- c i e s a r e t h e same i n a l l c a s e s a n d / o r i n p a r t i c u l a r t h e number o f v a c a n c i e s a s s o c i a t e d w i t h 5 7 ~ o / 5 7 ~ e i s much t h e same. I n t h e l a t t e r c a s e , t h e number i s t h o u g h t t o be a s small as i n t h e A1-0.02 a t z s 7 ~ e a l l o y / 2 , 3 / .
The specimen was f i r s t quenched from 873 K and aged a t room t e m p e r a t u r e f o r 5 min. The Mijss- bauer s p e c t r a were measured a t s e v e r a l t e m p e r a t u r e s from 78 K t o 293 K w i t h o u t changing t h e geometry b e t w e z n a Msssbauer apparatus and t h e specimen. A f - t e r each measurement above 193 K a measurement a t 78 K was followed t o check
i f
t h e r e i s any change i n t h e spectrum d u r i n g t h e measurement.In f i g u r e 2 , t e m p e r a t u r e dependence o f l i n e i n t e n s i t i e s w i t h two peaks was f i t t e d t o r e c o i l l e s s f r a c t i o n b y Debye model. The c h a r a c t e r i s t i c tempe- r a t u r e s
o4
were 235 K and 300 K f o r t h e s o l i d so-+ D ~
l u t i o n and vacancy peak, r e s p e c t i v e l y . The Debye t e m p e r a t u r e s i n d i c a t e t h a t t h e f o r c e c o n s t a n t f o r Co atoms a s s o c i a t e d w i t h v a c a n c i e s i s h i g h e r t h a n t h a t o f Co i n s o l i d s o l u t i o n . I t i s n o t c o n s i s t e n t w i t h t h e former r e s u l t 131, and t h e f u r t h e r s t u d y
1
I I I I I100 200 300
temperature K
F i g . 2 : Temperature dependence o f normalized l i n e i n t e n s i t i e s o f t h e two peaks.
The d e t e c t i o n o f t h e jumping f r e q u e n c y o f t h e i m p u r i t y atoms c a r r i n g v a c a n c i e s i s i m p o r t a n t i n o r d e r t o throw l i g h t o n t h e low t e m p e r a t u r e ageing b e h a v i o r o f aluminium a l l o y s . The w i d t h increment o f Nsssbauer spectrum should b e r e l a t e d l i n e a r l y w i t h t h e jumping p r o b a l i t y 151. I n t h e l i n e w i d t h s d u r i n g t h e above experiment up t o 273 K , no such an increment appeared w i t h i n t h e accuracy o f t h e ex- p e r i m e n t , s u g g e s t i n g t h a t thermal d r i f t o f Co atoms c a r r i n g v a c a n c i e s was slow i n t h e t e m p e r a t u r e range.
At above 284 K , t h e area o f t h e vacancy peak decrea- s e d . At t h e same t i m e t h e l i n e w i d t h i n c r e a s e d and t h e ~ o s i t i o n s h i f t e d a l i t t l e toward h i e h e r energy s i d e . S i m i l a r l y i n t h e i s o c h r o n a l a n n e a l i n g / 3 / , l i n e p o s i t i o n and w i d t h changed w i t h t h e decay o f t h e peak. They s u g g e s t t h e d e t r a p p i n g and t h e agglo- m e r a t i o n o f v a c a n c i e s . The above w i d t h i n c r e m e n t , t h e r e f o r e , may be due t o t h e same r e a s o n .
R e f e r e n c e s
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