HAL Id: jpa-00225378
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Submitted on 1 Jan 1985
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ELASTIC CONSTANT SOFTENING AND
SHORT-RANGE ORDERING PHENOMENA IN
METAL-HYDROGEN SYSTEMS
F. Mazzolai, H. Birnbaum
To cite this version:
JOURNAL D E PHYSIQUE
Colloque C10, supplement au 11-12, Tome 46, decembre 1985 page C10-81
ELASTIC CONSTANT SOFTENING AND SHORT-RANGE ORDERING PHENOMENA IN METAL-HYDROGEN SYSTEMS
F.M. MAZZOLAI AND
H.K.
BIRNBAUM'Dipartimento di Fisica, universita degli Studi d i Perugia, Perugia , Italy
'Department of Metallurgy and Mining Engineering and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
Stress induced short-range o r d e r changes, which g i v e r i s e t o a n e l a s t i c r e l a x a t i o n processes (Zener e f f e c t s ) have been found t o occur i n several metal-hydrogen systems, such as Pd-H, Pg-Ag-H, Nb-H and Zr-H. The main
r e s u l t s o b t a i n e d so f a r i n v a r i o u s Me-H systems w i l l be reviewed and t h e p e r s p e c t i v e s f o r f u r t h e r work examined.
P a r t i c u l a r a t t e n t i o n w i l l be p a i d t o t h e b - H system where e l a s t i c constant s o f t e n i n g e f f e c t s i n t h e a ' phase have been observed on approaching t h e a'+B t r a n s i t i o n temperature. The composition dependent e l a s t i c moduli changes were shown t o c o n s i s t o f a temperature independent and a temperature dependent p a r t . The temperature independent changes were analyzed on t h e b a s i s o f c o n t r i b u t i o n s due t o volume changes and t o changes i n t h e e l e c t r o n i c s t r u c t u r e o f t h e a l l o y . The temperature dependent c o n t r i b u t i o n s t o t h e e l a s t i c moduli changes were each associated w i t h an a c o u s t i c a t t e n u a t i o n and e x h i b i t e d a s i g n i f i c a n t i s o t o p i c dependence. It was shown t h a t t h e r e s u l t s a r e c o n s i s t e n t w i t h a r e l a x a t i o n due t o stress-induced changes i n t h e s h o r t - range o r d e r o f t h e H i n t e r s t i t i a l s i .e. a Zener r e l a x a t i o n .
