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GRAIN BOUNDARY RELAXATION IN SOLID SOLUTIONS AND INTERNALLY OXIDIZED
ALLOYS
G. Ashmarin, M. Golubev, A. Zhikharev, Y. Shvedov
To cite this version:
G. Ashmarin, M. Golubev, A. Zhikharev, Y. Shvedov. GRAIN BOUNDARY RELAXATION IN
SOLID SOLUTIONS AND INTERNALLY OXIDIZED ALLOYS. Journal de Physique Colloques,
1987, 48 (C8), pp.C8-401-C8-405. �10.1051/jphyscol:1987860�. �jpa-00227164�
GRRIN BOUNDARY RELAXATION IN SOLID SOLUTIONS AND INTERNALLY OXIDIZED ALLOYS
G.M. ASHMARIN, M.Y. GOLUBEV, A . I . ZHIKHAREV a n d Y.A. SHVEDOV Department of Physics, Moscow Institute of Steel and Alloys, Leninskij Prospekt 4, Moscow, USSR
A b s t r a c t : Grain boundary r e l a x a t i o n o f i r o n based s o l i d s o l u t i o n s shows s t r o n g e r dependence on g r a i n s i z e t h a n f o r t h e p u r e m?tal. I n s o l u b l e p a r t i c l e s i n g r a i n boundaries o f copper s u p p r e s s g r a i n boundary r e l a x a t i o n and d e c r e a s e t h e peak temperature with t h e d e c r e a s e o f t h e i n t e r p a r t i c l e d i s t a n c e . When t h e l a s t i s l e s s t h a n 0.5 p t h e peak d i s a p p e a r s .
The u n d e r s t a n d i n g of t h e mechanism of t h e g r a i n boundary i n t e r n a l f r i c t i o n badly needs t h e knowledge about t h e i n f l u e n c e o f t h e average g r a i n s i z e and i n s o l u b l e p a r t i c l e s o f t h e s t r e n g t h - g i v i n g phase on t h e f e a t u r e s of t h e r e l a x a t i o n spectrum of t h e m a t e r i a l .
TEM and o p t i c a l microscopy examination a s w e l l a s i n t e r n a l f r i c t i o n measurements f o r s o l i d s o l u t i o n s Fe-Si, Fe-Sn, Fe-Re and Fe-Ti w i t h d i f f e r e n t g r a i n s i z e and f o r copper specimens a l l o y e d by Sn. S i o r B and s a t u r a t e d by oxygen a t f i x e d temperatures have been c a r r i e d o u t . The i n t e r n a l f r i c t i o n h a s been measured i n t h e i n v e r t e d t o r s i o n pendulum a t t h e frequency about 1 Hz with wire specimens of 0.8 mm d i a m e t e r and 60 mm l e n g t h . The experimental procedure and d a t a treatment t a k i n g i n t o account t h e peak widening a r e given i n [ I ] .
F i g . 1 r e p r e s e n t s t h e dependence o f t h e g r a i n boundary (GBP) and i m p u r i t y g r a i n boundary (IGBP) peak r e l a x a t i o n s t r e n g t h on t h e g r a i n s i z e ( r a n g e 30-300 p). A l l a l l o y s s t u d i e d show a d e c r e a s e of t h e r e l a x a t i o n s t r e n g t h A f o r GBP and IGBP with i n c r e a s i n g g r a i n s i z e which is s a t i s f a c t o r i l y d e s c r i b e d by t h e e q u a t i o n &-d-m, where m = 0.2
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0.6.The a n a l y s i s of t h e r e s u l t s o b t a i n e d t o g e t h e r w i t h t h e l i t e r a t u r e d a t a shows s t r o n g e r dependence o f t h e r e l a x a t i o n s t r e n g t h on t h e g r a i n s i z e f o r IGBP i n s o l i d s o l u t i o n s t h a n t h e GBP i n p u r e m e t a l s . We can a l s o s e e t h a t t h e i m p u r i t y n o t i c e a b l y i n t e n s i f i e s t h e dependence o f GBP and IGBP r e l a x a t i o n s t r e n g t h on g r a i n s i z e .
Such r e g u l a r i t i e s can b e e x p l a i n e d from t h e p o i n t of view o f t h e d i s l o c a t i o n model o f t h e g r a i n boundary r e l a x a t i o n [2-41, a c c o r d i n g t o which t h e g r a i n boundary peak r e l a x a t i o n s t r e n g t h i s p r o p o r t i o n a l t o t h e g r a i n boundary d i s l o c a t i o n (GBD) d e n s i t y P, t h e squared d i s t a n c e L between t h e s t r o n g p i n n i n g p o i n t s and t h e r e c i p r o c a l o f t h e average g r a i n s i z e i n t h e specimens :
A-PL~ /d
For m e t a l s with high enough s t a c k i n g f a u l t energy t h e s t r o n g p i n n i n g p o i n t s can b e made mainly by t h e i n t e r s e c t i o n o f t h e l a t t i c e d i s l o c a t i o n s with g r a i n boundary. I n t h i s c a s e t h e dependence o f GBP r e l a x a t i o n s t r e n g t h on t h e g r a i n s i z e is defined by t h e change of t h e g r a i n boundary and volume d i s l o c a t i o n s t r u c t u r e i n t h e g r a i n forming p r o c e s s of r e c r y s t a l l i s a t i o n and p o s s i b l e i n c r e a s e of t h e average
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1987860
C8-402 JOURNAL DE PHYSIQUE
s i z e o f t h e Frank network c e l l . The d e c r e a s e o f t h e average s u r f a c e d e n s i t y of CBDs and volume d e n s i t y o f l a t t i c e d i s l o c a t i o n s w h i l e a n n e a l i n g due t o t h e tendency of t h e i n t e r c r y s t a l l i n e s u r f a c e s t o d e c r e a s e i t s f r e e energy when approaching the s p e c i a l boundary o r i e n t a t i o n .
A l l t h e s e f a c t o r s can l e a d t o t h e independence o r v e r y weak dependence of the GBP r e l a x a t i o n s t r e n g t h on g r a i n s i z e i n pure m e t a l s a s observed 15-71.
The atoms o f a l l o y i n g element i n t e r a c t i n g w i t h t h e l a t t i c e d i s l o c a t i o n s d e c r e a s e t h e i r c l i m b i n g v e l o c i t y which s h o u l d l e a d t o t h e slower growth of t h e Frank network c e l l s i n g r a i n s compared w i t h t h e p u r e metals. That i s why t h e d e c r e a s e o f GBP r e l a x a t i o n s t r e n g t h i n a l l o y s due t o t h e i n c r e a s e o f t h e g r a i n s i z e i s more i n t e n s i v e than t h a t of pure metal. The exponent m should i n c r e a s e with the i m p u r i t y c o n t e n t s as i t was observed i n s o l u t i o n s [8. 91.
E v i d e n t l y . d i s c u s s i n g t h e mechanism of a n e l a s t i c l o s s e s due t o i n t e r c r y s t a l l i n e s u r f a c e s one should t a k e i n t o account t h e e x i s t e n c e n o t only of t h a t k i n d o f d e f e c t s b u t o f t r i p l e p o i n t s as w e l l . Such p o i n t o f view needs t h e examination a l o n g w i t h t h e g r a i n boundary s l i d i n g and t h e p o s s i b i l i t i e s o f i t s accomodation i n t h e t r i p l e p o i n t r e g i o n which is more d e f e c t i v e than an i n t e r g r a i n s u r f a c e . However t h e c o n t r i b u t i o n o f t h i s p r o c e s s t o t h e energy d i s s i p a t i o n on i n t e r c r y s t a l l i n e s u r f a c e s i s n o t c l e a r e d o u t y e t .
The r e s u l t s o f t h i s s t u d y o f t h e o x i d e p a r t i c l e s d i s t r i b u t i o n i n t h e volume and on t h e boundaries i n copper a s w e l l a s t h e l i t e r a t u r e d a t a on t h e s t r u c t u r e and composition o f copper based i n t e r n a l l y o x i d i z e d a l l o y s a l l o w t o c o n s i d e r p r e c i p i t a t e d p a r t i c l e s of t h e o x i d e s SiO,, SnO,, Bz03 up t o 1000 K a s s t a b l e ( i . e . t h e i r d i s t r i b u t i o n parameters i n t h e volume and on t h e boundary a r e unchangeable).
The c o n c e n t r a t i o n o f a l l o y i n g elements i n s o l i d s o l u t i o n a f t e r i n t e r n a l o x i d a t i o n i s very low and does not i n f l u e n c e t h e i n t e r n a l f r i c t i o n o f t h e s e m a t e r i a l s . The o x i d e p a r t i c l e s i n copper a r e i n c o h e r e n t and do n o t g i v e s i g n i f i c a n t s t r u c t u r a l d i s t o r t i o n o f t h e m a t r i x . Taking i n t o account t h e s e c o n s i d e r a t i o n s and a l s o t h e f a c t t h a t t h e i n t e r n a l o x i d i z i n g temperature i s k e p t t h e same f o r t h e forming i d e n t i c a l i n t e r g r a n u l a r s t r u c t u r e l e a d s t o t h e c o n c l u s i o n of t h e e x i s t e n c e of a s t r o n g e r dependence (compared t o s u b s t i t u t i o n a l s o l i d s o l u t i o n s ) of t h e GBP r e l a x a t i o n s t r e n g t h on t h e g r a i n s i z e ( m = 1) i n m e t a l s with second phase oxide p a r t i c l e s .
T h i s assumption a l l o w s t o compare parameters o f t h e g r a i n boundary peak i n copper d i f f u s i o n a l y s a t u r a t e d by oxygen a t t h e temperature o f t h e i n t e r n a l o x i d i z i n g of a l l o y s with GBP parameters expected f o r t h e s e m a t e r i a l s with copper g r a i n s i z e .
Comparing t h e s e r e s u l t s w i t h e l e c t r o n microscopy d a t a one can make t h e f o l l o w i n g c o n c l u s i o n s :
1. The i n c r e a s e o f t h e number of o x i d e p a r t i c l e s on t h e i n t e r g r a n u l a r s u r f a c e d e c r e a s e s t h e r e l a x a t i o n s t r e n g t h A o f t h e g r a i n boundary peak. Alloys Cu-SiO, show i t s complete disappearance when t h e d i s t a n c e between t h e p a r t i c l e s o f SiO, i n t h e i n t e r g r a n u l a r s u r f a c e is l e s s t h a n 0.5 p ( p a r t i c l e s i z e 0 . 2 p ) . I n t h i s c a s e t h e p i n n i n g d e g r e e o f t h e i n t e r g r a n u l a r boundary ( t h e r a t i o o f t h e a r e a pinned by t h e p a r t i c l e s t o t h e t o t a l boundary a r e a ) by t h e s t r e n g t h e n i n g phase i s equal t o 0.16.
2. The d e c r a s e A of t h e p o l y c r y s t a l l i n e i n t e r n a l l y o x i d i z e d copper a l l o y s is d e f i n e d by t h e d i s t a n c e L between p a r t i c l e s of t h e second phase and does n o t depend of t h e i r n a t u r e and shape.
3. Temperature o f t h e g r a i n boundary peak d e c r e a s e s with t h e d e c r e a s e of t h e i n t e r p a r t i c l e d i s t a n c e and a l s o depends o n l y on t h e boundary a r e a p e r p a r t i c l e .
r e l a x a t i o n model proposed by t h e a u t h o r s [2]. According t o t h i s model t h e g r a i n boundary peak o r i g i n a t e s from t h e energy d i s s i p a t i o n by v i b r a t i n g segments of screw boundary d i s l o c a t i o n s with t h e edge component. The a c t i v a t i o n energy depends on t h e n a t u r e o f t h e metal and is defined by t h e kind of t h e d i f f u s i o n a l process predominating a t t h e s e temperatures
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boundary s e l f - d i f f u s i o n f o r m e t a l s with low v a l u e s o f t h e s t a c k i n g f a u l t energy o r volume s e l f - d i f f u s i o n f o r m e t a l s with s l i g h t l y s p l i t e d d i s l o c a t i o n s .The d i s p e r s i o n p a r t i c l e s of t h e second phase i n t r o d u c e d t o an i n t e r g r a n u l a r s u r f a c e l e a d t o t h e disappearance of p a r t of d i s l o c a t i o n network and t o t h e appearance o f t h e a d d i t i o n a l s t r o n g p i n n i n g p o i n t s f o r t h e g r a i n boundary d i s l o c a t i o n s . The number o f jogs w i t h edge c h a r a c t e r d e c r e a s e s and hence t h e vacancy flow is reduced. That i s why t h e r e l a x a t i o n s t r e n g t h o f t h e g r a i n boundary peak i n i n t e r n a l l y o x i d i z e d copper a l l o y s and peak temperature d e c r e a s e with t h e i n c r e a s e of t h e number o f i n e r t p a r t i c l e s on t h e i n t e r g r a n u l a r s u r f a c e .
The modeling of t h i s p r o c e s s
[lo]
according t o t h e e q u a t i o n s [2,41
f o r GBP r e l a x a t i o n s t r e n g t h and p r e - e x p o n e n t i a l c o e f f i c i e n t of t h e r e l a x a t i o n time g i v e s good c o r r e l a t i o n o f t h e normalized r e l a x a t i o n s t r e n g t h and t h e peak temperature with t h e experimental r e s u l t s ( f i g . 2 ) .One s h o u l d a l s o be mention t h e i n c r e a s e o f t h e GBP r e l a x a t i o n s t r e n g t h of non-alloyed copper a f t e r d i f f u s i o n a l s a t u r a t i o n by oxygen. D i f f u s i o n a l s a t u r a t i o n of copper b i n d s r e s i d u a l i m p u r i t y atoms absorbed i n t h e g r a i n boundaries i n t o oxide p a r t i c l e s and d e c r e a s e s t h e number of a d d i t i o n a l p i n n i n g p o i n t s f o r g r a i n boundary d i s l o c a t i o n s . That l e a d s t o t h e i n c r e a s e o f GBP r e l a x a t i o n s t r e n g t h . Copper r e f i n i n g d u r i n g i n t e r n a l o x i d i z i n g is proved by t h e i n c r e a s e of t h e e l e c t r o c o n d u c t i v i t y compared with i n i t i a l s t a t e .
Doubtless i n t e r e s t has t h e v a l u e of t h e g r a i n boundary p i n n i n g degree 8 by t h e p r e c i p i t a t e s found experimentaly e q u a l t o
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0 , l 6 which l e a d s t o complete d i s a p p e a r a n c e of t h e g r a i n boundary peak.When w e assume t h e i n f l u e n c e of 8 on t h e GBP r e l a x a t i o n s t r e n g t h i s i d e n t i c a l t o t h e f i l l i n g degree 0,, o f t h e i n t e r g r a n u l a r s u r f a c e by t h e i m p u r i t i e s , t h e value
ex
= 0 , 1 6 i s i n good agreement with t h e c r i t i c a l values 8; = 0 . 1-
0 , 3 [4] and confirms t h e v a l i d i t y of t h e method suggested e a r l i e r f o r c a l c u l a t i o n of t h e i n t e r a c t i o n energy of t h e s u b s t i t u t i o n a l atoms w i t h t h e g r a i n boundary :where T; and C;
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peak temperature and c o n c e n t r a t i o n o f t h e a l l o y i n g element (both e x t r a p o l a t e d ) corresponding t o t h e moment o f complete d i s a p p e a r a n c e of g r a i n boundary peak.C8-404 JOURNAL DE PHYSIQUE
So
F e S i20 10
Fig. 2
Fig. 1
Fig. 1. Dependence o f t h e r e l a x a t i o n s t r e n g t h of t h e g r a i n boundary peak ( I ) and t h e g r a i n boundary i m p u r i t y peak (11) on t h e average g r a i n s i z e f o r i r o n s o l i d s o l u t i o n s :
Fig. 2. C o r r e l a t i o n between t h e o r e t i c a l ( l - f o r p r e c i p i t a t i o n s i z e D, = 0 p ; 2 - f o r D, = 0,3 P) and e x p e r i m e n t a l v a l u e s of t h e r e l a x a t i o n s t r e n g t h and temperature of t h e g r a i n boundary peak i n copper with o x i d e p a r t i c l e s o f S i , Sn. B and Ge
uniformly d i s t r i b u t e d a l o n g t h e g r a i n boundary. The v a l u e s A,/% f o r a l l o y s marked by t h e a s t e r i s k a r e c a l c u l a t e d u s i n g t h e d a t a [ll].
1. Zhikkarev A.I., Ashmarin G.M., Shvedov Ye.A.- Y z v e s t i j a WZov. Chernaja m e t a l l u r g i j a , 1980, N'
3.
p. 103-106.2 . Shvedov Ye.A., Zhikharev A . I . , Ashmarin G.M.- P h y s i c a i c h i m i j a o b r a b o t k i m a t e r i a l o v . 1979, N o 5 , p. 62-68.
3. Ashmarin G.M.. Zhikharev A . I . . Shvedov Ye.A.- R e f e r a t y I X Konferencja metalooznawcza. Krakow. 1977, p. 391-400.
4. Ashmarin G.M., Zhikharev A . I . , Shvedov Ye.A.- "Radex-Rundschau". 1982, h. 3, p. 871-876.
5. Roberts I.T.A.. Barrand P.- J. I n s t . Metals. 1968, v. 96, N* 6. p. 172-177.
6. Leak G.M.- Proc. Roy. Soc.. London. 1961, v. 7 8 , p. 1520-1528.
7. Williams M.W.. Leak G.M.- Acta met.. 1967, v . 15. p . 1111-1118.
8. Barrand P.- Acta met., 1966, v .
14,
p. 1247-1256.9 . Gridnev V.N., Efimov A . I . , Kushnareva N.P.- I n book : Metal1ophysica.- Kiev, Naukova dumka. 1974. N' 49. p. 54-62.
10. Ashamarin G.M., Golubev M.Y., D a n e l i j a Ye.P.- I n book : V n u t r e m e e t r e n i e i tonkoe s t r o e n i e metallov i neorganicheskikh materia1ov.- Moscow. Nauka. 1985, p. 80-85.
11. Mosher D.R., Raj R.- Acta met., 1974, v. 22, N' 1 2 , p. 1469-1474.
