- Email: [email protected]
Reply to remarks on “The energy-misorientation relationship of grain boundaries”
Scripta METALLURGICA
Vol. 14, pp. 1161-1162, 1980 Printed in the U.S.A.
REPLY TO REMARKS ON "THE ENERGY-MISORIENTATION
Pergamon Press Ltd. All rights reserved
RELATIONSHIP
OF GRAIN BOUNDARIES"
H. G l e i t e r , University of SaarbrUcken, D-6600 S a a r b r U c k e n , W.-Germany
(Received August 4, 1980)
In a r e c e n t n o t e ( I ) t h e e x p e r i m e n t s and i n t e r p r e t a t i o n s by Kuhn e t a l . (2) were c r i t i c i z e d i n terms o f t h e number and a c c u r a c y o f t h e d a t a p o i n t s p r e s e n t e d . As some o f th e c r i t i c i s m s seem t o d i s a g r e e w i t h e x p e r i m e n t a l f a c t s , we would l i k e t o comment on t h e remarks made i n r e f . (I (I
We a g r e e t h a t more d a t a and a h i g h e r a c c u r a c y seem d e s i r a b l e . N e v e r t h e l e s s i t s h o u l d n o t be o v e r l o o k e d t h a t one o f t h e pr ime g o a l s o f r e f . (2) was to d e s c r i b e and a p p l y a new method f o r mapping cusps of the boundary e n e r g y - m i s o r i e n t a t i o n c u r v e w i t h an a c c u r a c y t h a t i s a t l e a s t one o r d e r o f m a g n i t u d e h i g h e r than the d a t a t h a t were a v a i l a b l e in the l i t e r a t u r e . In f a c t , t h e e n e r g y cusps mapped i n r e f . (2) have n o t even be r e v e a l e d by t h e e a r l i e r measurements. F u r t h e r more t h e e x p e r i m e n t s o f Kuhn e t a l . (2) seem t o be t h e f i r s t direct o b s e r v a t i o n s o f t h e e n e r g y cusps a t o r i e n t a t i o n relationships that a r e n o t p r e d i c t e d i n terms o f h i g h c o i n c i d e n c e s i t e d e n s i t y m o d e l s .
2
The d a t a were a n a l y s e d by c o n s i d e r i n g a l l f i v e d e g r e e s o f f r e e d o m o f a g r a i n b o u n d a r y . In f a c t , o n l y t h o s e s p h e r e s were used f o r t he measurements w h i c h formed a g r a i n b o u n d a r y t h a t was p a r a l l e l to t he c r y s t a l p l a t e and t h a t r e m a i n e d c o n s t a n t d u r i n g a l l t r e a t m e n t s . The boundary p o s i t i o n was d e r i v e d from t he shape o f t h e s u r f a c e g r o o v e .
3
The Shewmon mechanism (3) was used to e v a l u a t e t h e d a t a because t he c o s i n e o f t h e a n g l e between t h e b o u n d a r y p l a n e and t h e a x i s o f r o t a t i o n was 0 . 9 5 i n both s p e c i m e n s . A d e v i a t i o n o f 5 % from u n i t y (as r e q u i r e d i d e a l l y f o r t h e Shewmon-Gessinger a n a l y s i s ( 3 ) , ( 4 ) ) , makes t h e d i s l o c a t i o n - g l i d e mechanism (5) n e g l i g i b l e .
4
C o n t r a r y t o t h e a s s u m p t i o n made i n r e f . ( i ) , rotation (6) were n o t used f o r t h e a n a l y s i s .
5
The p r o p o s a l t h a t a s l o w - d o w n o f t h e s p h e r e s may be due t o t h e i n efficiency o f g r a i n b o u n d a r i e s as vacancy s o u r c e s i s i n c o n t r a d i c t i o n t o t h e r o t a t i o n k i n e t i c s o b s e r v e d f o r s ma ll a n g l e b o u n d a r i e s , = 3 and ~ = I I b o u n d a r i e s .
6
A l t h o u g h i t i s n o t t h e p u r p o s e o f t h i s n o t e t o comment on t h e c o r e width of secondary grain boundary dislocations, i t r e m a i n s t o be shown t h a t t h e a c c u r a c y o f t h e e v i d e n c e p r e s e n t e d i n f a v o u r o f s har p e n e r g y cusps and l o c a l i z e d d i s l o c a t i o n c o r e s i s h i g h e r t h a n t he q u e s t i o n e d a c c u r a c y o f t h e e n e r g y measurements ( 2 ) .
s p h e r e s showing anomalous
1161 OQ36-9748/SQ/IOII61~0252.00/O Copyright (c) 1980 Pergamon Press Ltd.
1162
ENERGY-MISORIENTATION RELATIONSHIP
Vol.
1 4 , No.
REFERENCES 1) A.H. King and R.W. B a l l u f f i , Scripta Met., this issue 2) H. Kuhn, G. B~ro and H. G l e i t e r , Acta Met. 27, 959 (1979) 3) P.G. Shewmon in R e c r y s t a l l i z a t i o n , Grain G r ~ t h and Textures, p. 165, ASM, Metals Park, Ohio 1966 4) G. Gessinger, F.V. Lenel and G.S. Ansell, Scripta Met. 2, 547 (1968) 5) R.C. Pond and D. Smith, Scripta Met., 1_~1, 77 (1977) 6) H. Mykura, Acta Met. 2__77, 243 (1979)
10
Vol. 14, pp. 1161-1162, 1980 Printed in the U.S.A.
REPLY TO REMARKS ON "THE ENERGY-MISORIENTATION
Pergamon Press Ltd. All rights reserved
RELATIONSHIP
OF GRAIN BOUNDARIES"
H. G l e i t e r , University of SaarbrUcken, D-6600 S a a r b r U c k e n , W.-Germany
(Received August 4, 1980)
In a r e c e n t n o t e ( I ) t h e e x p e r i m e n t s and i n t e r p r e t a t i o n s by Kuhn e t a l . (2) were c r i t i c i z e d i n terms o f t h e number and a c c u r a c y o f t h e d a t a p o i n t s p r e s e n t e d . As some o f th e c r i t i c i s m s seem t o d i s a g r e e w i t h e x p e r i m e n t a l f a c t s , we would l i k e t o comment on t h e remarks made i n r e f . (I (I
We a g r e e t h a t more d a t a and a h i g h e r a c c u r a c y seem d e s i r a b l e . N e v e r t h e l e s s i t s h o u l d n o t be o v e r l o o k e d t h a t one o f t h e pr ime g o a l s o f r e f . (2) was to d e s c r i b e and a p p l y a new method f o r mapping cusps of the boundary e n e r g y - m i s o r i e n t a t i o n c u r v e w i t h an a c c u r a c y t h a t i s a t l e a s t one o r d e r o f m a g n i t u d e h i g h e r than the d a t a t h a t were a v a i l a b l e in the l i t e r a t u r e . In f a c t , t h e e n e r g y cusps mapped i n r e f . (2) have n o t even be r e v e a l e d by t h e e a r l i e r measurements. F u r t h e r more t h e e x p e r i m e n t s o f Kuhn e t a l . (2) seem t o be t h e f i r s t direct o b s e r v a t i o n s o f t h e e n e r g y cusps a t o r i e n t a t i o n relationships that a r e n o t p r e d i c t e d i n terms o f h i g h c o i n c i d e n c e s i t e d e n s i t y m o d e l s .
2
The d a t a were a n a l y s e d by c o n s i d e r i n g a l l f i v e d e g r e e s o f f r e e d o m o f a g r a i n b o u n d a r y . In f a c t , o n l y t h o s e s p h e r e s were used f o r t he measurements w h i c h formed a g r a i n b o u n d a r y t h a t was p a r a l l e l to t he c r y s t a l p l a t e and t h a t r e m a i n e d c o n s t a n t d u r i n g a l l t r e a t m e n t s . The boundary p o s i t i o n was d e r i v e d from t he shape o f t h e s u r f a c e g r o o v e .
3
The Shewmon mechanism (3) was used to e v a l u a t e t h e d a t a because t he c o s i n e o f t h e a n g l e between t h e b o u n d a r y p l a n e and t h e a x i s o f r o t a t i o n was 0 . 9 5 i n both s p e c i m e n s . A d e v i a t i o n o f 5 % from u n i t y (as r e q u i r e d i d e a l l y f o r t h e Shewmon-Gessinger a n a l y s i s ( 3 ) , ( 4 ) ) , makes t h e d i s l o c a t i o n - g l i d e mechanism (5) n e g l i g i b l e .
4
C o n t r a r y t o t h e a s s u m p t i o n made i n r e f . ( i ) , rotation (6) were n o t used f o r t h e a n a l y s i s .
5
The p r o p o s a l t h a t a s l o w - d o w n o f t h e s p h e r e s may be due t o t h e i n efficiency o f g r a i n b o u n d a r i e s as vacancy s o u r c e s i s i n c o n t r a d i c t i o n t o t h e r o t a t i o n k i n e t i c s o b s e r v e d f o r s ma ll a n g l e b o u n d a r i e s , = 3 and ~ = I I b o u n d a r i e s .
6
A l t h o u g h i t i s n o t t h e p u r p o s e o f t h i s n o t e t o comment on t h e c o r e width of secondary grain boundary dislocations, i t r e m a i n s t o be shown t h a t t h e a c c u r a c y o f t h e e v i d e n c e p r e s e n t e d i n f a v o u r o f s har p e n e r g y cusps and l o c a l i z e d d i s l o c a t i o n c o r e s i s h i g h e r t h a n t he q u e s t i o n e d a c c u r a c y o f t h e e n e r g y measurements ( 2 ) .
s p h e r e s showing anomalous
1161 OQ36-9748/SQ/IOII61~0252.00/O Copyright (c) 1980 Pergamon Press Ltd.
1162
ENERGY-MISORIENTATION RELATIONSHIP
Vol.
1 4 , No.
REFERENCES 1) A.H. King and R.W. B a l l u f f i , Scripta Met., this issue 2) H. Kuhn, G. B~ro and H. G l e i t e r , Acta Met. 27, 959 (1979) 3) P.G. Shewmon in R e c r y s t a l l i z a t i o n , Grain G r ~ t h and Textures, p. 165, ASM, Metals Park, Ohio 1966 4) G. Gessinger, F.V. Lenel and G.S. Ansell, Scripta Met. 2, 547 (1968) 5) R.C. Pond and D. Smith, Scripta Met., 1_~1, 77 (1977) 6) H. Mykura, Acta Met. 2__77, 243 (1979)
10