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Submitted on 1 Jan 1981
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INTRODUCTION FOR THE POINT DEFECT RELAXATION SESSION
P. Moser
To cite this version:
P. Moser. INTRODUCTION FOR THE POINT DEFECT RELAXATION SESSION. Journal de
Physique Colloques, 1981, 42 (C5), pp.C5-721-C5-722. �10.1051/jphyscol:19815110�. �jpa-00220979�
JOURNAL DE PHYSIQUE
CoZZoque C5, suppZdrnent au nOIO, Tome 4 2 , octobre 1981 page C5-72 1
INTRODUCTION FOR THE POINT DEFECT RELAXATION SESSION
P. Moser
Centre d 'Etudes Nucldaires de GrenobZe, Dbparternent de Recherche FondamentaZe S e c t i o n de Physique du SoZ.i.de, 85 X , 38041 GrenobZe Cedes, i+ance
The session about Snoek type r e l a x a t i o n i s very r i c h i n new r e s u l t s since more than f i f t y new peaks a r e evidenced and characterized.
There i s t h r e e main subjects, w i t h about 113 o f t h e papers i n each domain:
1. R e l a x a t i o n o f I r r a d i a t i o n Defects: Mo, C r and A1 a l l o y s 2. Relaxation o f A l l o y s w i t h hydrogen:
-
b i n a r y a l l o y s :&
H-
t e r n a r y a l l o y s :Nb -
0-H,5 -
N-H,-
Ti-H,-
N-H,2 -
A1-H,1 -
Ti-H-
quaternary a1 l o y s : Ti-V-A1-H3. Relaxation o f A l l o y s w i t h o u t hydrogen:
-
b i n a r y z-N, E - 0 , z - C , E - 0-
t e r n a r y *-Ti -N,
E - T i -N,
fe-V-N,
Ce-02.. .
y3+A very accurate atomic model f o r e x p l a i n i n g t h e observed r e l a x a t i o n modes i s given i n more than 60% o f t h e papers. Several authors use t h e i r pendulum as a s u p e m i c r o - scope. B u t most o f these Microscopic models a r e es tab1 ished o n l y w i t h MAcroscopi c observations and they have few chances t o s u r v i v e when improvements i n p u r i t y o r i n e l e c t r o n i c w i l l a l l o w b e t t e r experiments. This i s the case f o r t h e b e a u t i f u l des- c r i p t i o n o f p a i r s and t r i p l e t s r e o r i e n t a t i o n i n TaO, born 22 years ago, and which i s n o t v e r i f i e d b y r e c e n t r e s u l t s . However, i t seems t h a t t h e Snoek model d e s c r i b i n g t h e carbon r e l a x a t i o n i n i r o n i s t i l l now u n i v e r s a l l y admitted !
A s t r i k i n g p o i n t w i l l be presented, showing t h a t d i f f i c u l t i e s a r i s e when i n t e r n a l f r i c t i o n r e s u l t s are compared t o those obtained by o t h e r techniques. F o r example a s t r o n g d i f f e r e n c e i s found between r e l a x a t i o n s t r e n g t h determined by i n t e r n a l f r i c t i o n o r Huang s c a t t e r i n g . Another example was given p r e v i o u s l y when i n t e r n a l f r i c t i o n was compared t o magnetic a f t e r e f f e c t (see W. Chambron e t a1
.,
I n t . Conf.on Fundamental Aspects o f Rad. Dam., Gatlinburg, Tennessee, USA, 1975, p. 438).
T h i s means t h a t these techniques do n o t "see" the d e f e c t as a geometrical p o i n t , b u t "see" i t as a small p e r t u r b e d r e g i o n surrounding t h e d e f e c t . So, t h e r e i s no reason t o observe the same s i z e o r symmetry degree when a d e f e c t i s s t u d i e d
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19815110
C5-722 JOURNAL DE PHYSIQLTE
simultaneously by d i f f e r e n t techniques.
And now, what about t h e f u t u r e o f t h i s v e r y o l d b u t extremely a c t i v e s p e c i a l i t y ? ( T h i s s p e c i a l i t y i s t h e e l d e s t o f t h i s conference, b u t if we consider t h a t 64 new peaks were discovered since
