HAL Id: jpa-00219648
https://hal.archives-ouvertes.fr/jpa-00219648
Submitted on 1 Jan 1980
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.
Fe DIMERS AND DEFECTS IN Cu
K. Krischel, S. Nasu, U. Gonser, W. Keune, J. Lauer, D. Williamson
To cite this version:
K. Krischel, S. Nasu, U. Gonser, W. Keune, J. Lauer, et al.. Fe DIMERS AND DEFECTS IN Cu. Journal de Physique Colloques, 1980, 41 (C1), pp.C1-417-C1-418. �10.1051/jphyscol:19801161�.
�jpa-00219648�
JOURNAL DE PHYSIQUE Colloque Cl
,
suppl6ment au n O 1, Tome 41, janvier 1980, page C 1-4 17Fe
DIMERS
AND DEFECTSIN
Cu+ +
K. Krischet,S, Ndsu; tJ. Goqs,e;er,. W. Keune , J. Lauer and D.L. Williamson K
Fachbereich Angewandte Physik5 &iivengifdt*.$es Suar.landes, 6600 SaarbrUcken, W-Germany.
+
GesamthochschuZe Duisburg, Labor fUr Angmandte Physik'~4200 Duisburg, W-Germany x CoZorado School of Mines, GoZden, CoZorado 80401, USA.The s o l u b i l i t y of Fe i n Cu a t room tem- p e r a t u r e i s o n l y 7x10-' a t . % a c c o r d i n g t o
e x t r a p o l a t i o n of h i g h t e m p e r a t u r e d a t a 1 ; however, 0.2 a t . % Fe i s s o l u b l e a t 891 K 2
.
By f a s t quenching t e c h n i q u e s u p e r s a t u r a - t e d a l l o y s c a n b e o b t a i n e d . The Mossbauer s p e c t r u m ( F i g . l a ) o f a Cu-0.2 a t . % Fe a l l o y which has been quenched from 1243 K i n t o w a t e r c a n be decomposed i n t o a s i n g - l e c e n t e r l i n e c o r r e s p o n d i n g t o i s o l a t e d Fe atoms w i t h 12 n e a r e s t n e i g h b o r Cu atoms, monomers, and a q u a d r u p o l e s p l i t l i n e r e p r e s e n t i n g m a i n l y Fe n e i g h b o r p a i r s , d i m e r s .
Velocity in mm/s
The r e l a t i v e a r e a s of t h e two s p e c t r a l components a r e r o u g h l y p r o p o r t i o n a l t o t h e f r a c t i o n of monomers ( 8 8 % ) and dimers
( 1 2%) ). These f r a c t i o n s c a n be changed de- pending on t h e quenching c o n d i t i o n s . The c e n t e r l i n e h a s a n isomer s h i f t o f 0.222 mm/sec r e l a t i v e t o
d
-Fe a t room tempera- t u r e and t h e q u a d r u p o l e s p l i t t i n g of t h e dimers i sA
E =0.639 mm/sec , a n d h a s a n isomer s h i f t of 0.189 mm/sec. 9A
E v a l u e s have b e e n r e p o r t e d 3 - 7 of somewhat s m a l l e r 9 magnitude ; however, t h i s i s ' i o be expec- t e d when t h e Fe a s s o c i a t i o n s o r c l u s t e r s 8 c o n s i s t on t h e a v e r a g e ,of more atoms ( t r i - mer, quadramer e t c . ) .S p e c t r a i n a p p l i e d l o n g i t u d i n a l m a g n e t i c f i e l d s o f SO and 70 kOe have been o b t a i n e d and decomposed i n t o monomer and dimer con- t r i b u t i o n s . F i g . 2 shows t h e r e s u l t o f t h e 70 kOe e x p e r i m e n t .
L l'
-
1 0 1 .2Velocity I m m l s l
F i g . 1 : Mossbauer s p e c t r a f o r Cu-0.2 a t . % F i g . 2 : Mossbauer s p e c t r a f o r Cu-0.2 a t . % Fe a l l o y , ( a ) a s quenched and (b) Fe i n a l o n g i t u d i n a l m a g n e t i c a s r o l l e d . Zero v e l o c i t y c o r r e s - f i e l d of 70 kOe. The l i n e r e p r e - ponds t o t h e c e n t e r o f t h e
d
-Fe s e n t s t h e c a l c u l a t e d s p e c t r u m . spectrum.Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19801161
Cl-418 JOURNAL DE PHYSIQUE
For t h e monomers t h e l o c a t i o n and r e l a t i - ve i n t e n s i t i e s of t h e f o u r l i n e s a r e e a s i - l y found. For t h e d i m e r s , t h e assumptions a r e j u s t i f i e d t h a t t h e e l e c t r i c f i e l d g r a - d i e n t , EFG, h a s a x i a l symmetry and t h a t t h e a n g u l a r dependence o f t h e q u a d r u p o l e h y p e r f i n e i n t e r a c t i o n comes from a random o r i e n t a t i o n of t h e dimers e v e n i n t h e p r e - s e n c e of a t e x t u r e d Cu m a t r i x . I n c o n t r a s t t o t h e s h a r p l i n e s o f t h e monomers t h e q u a d r u p o l e i n t e r a c t i o n of t h e dimers
-
p e r t u r b e d by t h e l o n g i t u d i n a l magnetic f i e l d
-
r e s u l t s i n broad r e s o n a n c e s . A t h e o r e t i c a l e v a l u a t i o n o f t h i s problem w i t h randomly o r i e n t e d p r i n c i p a l a x e s of t h e EFG-
w i t h p o s i t i v e and n e g a t i v e s i g n h a s been made. I t t u r n s o u t t h a t t h e c a l - c u l a t e d s p e c t r a of t h e d i m e r s i n a mag- n e t i c f i e l d a r e r a t h e r s i m i l a r f o r b o t h s i g n s of t h e EFG, however, a b e t t e r f i t t o t h e e x p e r i m e n t a l s p e c t r u m , a s i n d i c a t e d by t h e x 2 - t e s t , was a c h i e v e d by assuming a n e g a t i v e s i g n of t h e EFG a s s u g g e s t e d by Window 4.
I t h a s b e e n a r g u e d t h a t Fe atoms on s u r f a c e s of c o h e r e n t Fe p r e c i p i t a t e s i n Cu have t h e o p p o s i t e-
a p o s i t i v e s i g n f o r t h e EFG'.S u b s e q u e n t l y , t h e specimen was p l a s t i c a l - l y deformed by c o l d r o l l i n g which reduced t h e t h i c k n e s s by a b o u t 6 0 % . A f t e r t h i s t r e a t m e n t t h e s p e c t r u m ( F i g . l b ) h a s b r o a - dened and t h e dimer c o n t r i b u t i o n i s h a r d l y d i s t i n g u i s h a b l e . Under d e f o r m a t i o n , motion of d i s l o c a t i o n s c o u l d c a u s e some d i m e r s b r e a k - u p s t o o c c u r . More i m p o r t a n t i n t h i s p r o c e s s seems t o be t h e c r e a t i o n of va- c a n c i e s and m u l t i p l i c a t i o n of d i s l o c a t i o n s . A t room t e m p e r a t u r e t h e s e v a c a n c i e s a r e m o b i l e 8
.
Because of t h e v a c a n c y - i m p u r i t yi n t e r a c t i o n t h e v a c a n c i e s w i l l t r a n s p o r t some Fe atoms t o t h e i r s i n k s c l o s e r t o d i s l o c a t i o n s , g r a i n b o u n d a r i e s and o t h e r d e f e c t s . I t i s a l s o p o s s i b l e t h a t new dimers and l a r g e r c l u s t e r s a r e formed.
Thus, t h e many l o c a l environments e x p e r i - enced by t h e Fe atoms a s s o c i a t e d w i t h t h e v a r i e t y of d e f e c t s s h o u l d l e a d t o a d i s t r i b u t i o n of isomer s h i f t s and quadru-
p o l e s p l i t t i n g s r e s u l t i n g i n a b r o a d r e - sonance such a s o b s e r v e d h e r e . The i n t e r - n a l s t r e s s a t Fe atoms i n t h e p r o x i m i t y o f t h e d e f e c t s may be a n i m p o r t a n t c a u s e of t h e o b s e r v e d b r o a d e n i n g . Other e f f e c t s ha- ve b e e n o b s e r v e d by p l a s t i c d e f o r m a t i o n of Cu-Fe a l l o y s ; however, i n t h e s e e x p e r i - ments t h e c l u s t e r i n g p r o c e s s e s were more advanced4
'
R e f e r e n c e z
1. S a l j e , G . , F e l l e r - K n i e p m e i e r , M . , Z . Metallkunde
69,
(1978) 167 2 . Williamson, D.L., E l l i o t , M.,J . Physique
C-2,
(1979) 601 3 . Window, B . ,J . Phys. C 3 , (1970) 323 4. Window, B . ,
P h i l . Mag.
26,
(1972) 6815 . Campbell, S . J . , C l a r k , P.E., L i d e l l , P.
R . ,
J . Phys.
g,
(1972) L 114 6 . H o r n s t e i n , F . , Ron, M . ,Acta Met. 22, (1974) 1537
-
7. C l a r k , P.E., Campbell, S . J . , J . Physique
C-2,
(1979) 6138 . C l a r k , P.E., Cadogan, J . M . , Yazxhi, M.
J . , Campbell, S . J . , J . Phys. F9, (1979) 379
9. Williamson, D.L., Nasu, S., Gonser, U . , Acta Met.
24,
(1976) 1003Acknowledgement
The s u p p o r t by t h e Deutsche Forschungsge- m e i n s c h a f t i s g r a t e f u l l y acknowledged.
