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Submitted on 1 Jan 1982
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STUDY OF DEFECTS IN β -CuZn WITH THE POSITRON ANNIHILATION TECHNIQUE
C. Platteau, D. Segers, M. Dorikens, L. Dorikens-Vanpraet, J. Janssen
To cite this version:
C. Platteau, D. Segers, M. Dorikens, L. Dorikens-Vanpraet, J. Janssen. STUDY OF DEFECTS IN
β-CuZn WITH THE POSITRON ANNIHILATION TECHNIQUE. Journal de Physique Colloques,
1982, 43 (C4), pp.C4-733-C4-733. �10.1051/jphyscol:19824119�. �jpa-00221969�
JOURNAL DE PHYSIQUE
Co1,Zoque C4, suppZdment au
n o 12,Tome 43, dicembre
1982page
C 4 - 7 3 3STUDY OF DEFECTS
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THE POSITRON ANNIHILATION TECHNIQUEC. P l a t t e a u , D . S e g e r s , M. D o r i k e n s , L. D o r i k e n s - V a n p r a e t and J . ~ a n s s e n *
Lzboratorim Kernfysica, Proeftuinstraat
8 6 , B-9000Gent, Belgium
*KuL, Departement Me tau Zkunde, de Croy laan
2, 8-3030Hever Lee, EeZgiurn
( A c c e p t e d 9 August 1982)
P o s i t r o n a n n i h i l a t i o n m e a s u r e m e n t s h a v e a l r e a d y b e e n p e r f o r m e d i n a number o f CuZn a l l o y s [ 1 , 2 , 3 1 i n o r d e r t o d e t e r m i n e t h o v a c a n c y f o r m a t i o n e n t h a l p y i n t h e CuZn-system. We m e a s u r e d t h e 5 1 1 keV p o s i t r o n a n n i h i l a t i o n l i n e s h a p e i n t h e t e m p e r a t u r e i n t e r v a l between OS a n d 500C. The m e a s u r e m e n t s were d o n e f i r s t i n c r e a s i n g t h e t e m p e r a t u r e ( s e e f i g u r e 1 : ) and a f t e r w a r d s d e c r e a s i n g t h e t e m p e r a t u r e ( s e e f i g u r e 1 : +). A s a p o s i t r o n s o u r c e we used 54Cu. w h i c h was o b t a i n e d b y n e u t r o n a c t i v a t i o n o f a p i e c e o f m a t e r i a l o f t h e same CuZn a l l o y ( 4 7 . 5 w.% Zn)
.
An S - p a r a m e t e r was d e f i n e d t o c h a r a c t e r i z e t h e 511 keV a n n i h i l a t i o n l i n e .The n o n - e q u i l i b r i u m d e f e c t s ( m a i n l y d i s l o c a t i o n s i n t r o d u c e d d u r i n g t h e p r e p a r a t i o n o f t h e s a m p l e and i r r a d i a t i o n i n d u c e d d i s l o c a t i o n l o o p s ) a r e c o m p l e t e l y a n n e a l e d o u t a t 300C. The r e c o v e r y p r o c e e d s i n two s t e p s : a f i r s t s t e p from OC t o 150C i s d u e t o a n n e a l i n g o u t o f d i s l o c a t i o n s b y a p o l y g o n i z a t i o n mechanism, t h e s e c o n d s t e p from 150C t o 3002 i s a s c r i b e d t o r e c r y s t a l l i z a t i o n and an i n c r e a s e o f t h o g r a i n s i z e s .
For t h e a n n e a l e d m a t e r i a l . t r a p p i n g o f p o s i t r o n s i n t h e r m a l l y i n d u c e d v a c a n c i e s i s s e e n a b o v e 100C. The mono-vacancy f o r m a t i o n e n t h a l p y was d e t e r m i n e d from t h e t h r e s h o l d t e m p e r a t u r e , l e a d i n g t o Ef=(0.55+/-3.03)eV a n d from t h e f i t o f t h e t r a p p i n g model t o t h e m e a s u r e d d a t a , r e s u l t i n g i n Ef- (0.56+/-0.04)eV.
C o n t r a r y t o t h e r e s u l t s p u b l i s h e d i n r e f . 2 , no i n f l u e n c e o f t h e o r d e r i n g p a r a m e t e r on t h e p o s i t r o n t r a p p i n g i n v a c a n c i e s i n t h e CuZn a l l o y c o u l d be d e t e c t e d . Above 49OC no c l e a r e v i d e n c e f o r t r a p p i n g i n a s e c o n d d e f e c t ( a s a r g u e d i n r e f . 2 a n d r e f . 3 ) s u c h a s f o r e x a m p l e t h e d i v a c a n c y c o u l d b e o b t a i n e d from o u r me~,;urements.
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Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19824119