OUR PRESENT UNDERSTANDING OF DISLOCATION DAMPING

HAL Id: jpa-00225417

https://hal.archives-ouvertes.fr/jpa-00225417

Submitted on 1 Jan 1985

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.

OUR PRESENT UNDERSTANDING OF

DISLOCATION DAMPING

K. Lücke

To cite this version:

JOURNAL DE PHYSIQUE

Colloque C I O , supplément au n012, Tome 46, décembre 1985 page CIO-145

OUR PRESENT UNDERSTANDING OF DISLOCATION DAMPING

K. LUCKE

Institut fiir allgemine Metallkunde and Metallphysik, Ruth,

D-5&QO Aachen,

F. R.

For u l t r a - p u r i t y copper t h e d i s l o c a t i o n m o b i l i t y has been i n v e s t i g a t e d by measuring damping and modulus d e f e c t i n t h e MHz- and kHz-range, i n order t o t e s t t h e v a l i d i t y o f t h e d i s l o c a t i o n resonance theory. Electron i r r a d i a t i o n s have been a p p l i e d i n order t o Vary t h e p i n n i n g p o i n t d e n s i t y . I n b o t h frequency ranges i n i t i a l d i f f i c u l t i e s occurred. I n t h e MHz-range a t l o w frequencies, t o o h i g h values were found f o r t h e damping, i n c o n t r a s t t o t h e modulus. It c o u l d be s h o w t h a t these were due t o a s e t o f l o n g l o o p

d i s l o c a t i o n s . I n t h e kHz-range t h e p i n n i n g p o i n t number obtained by damping turned out t o be smaller than t h a t obtained by modulus change. This

discrepancy c o u l d q u a n t i t a t i v e l y be understood by t a k i n g i n t o account d e v i a t i o n s from t h e s t a t i s t i c a l l o o p l e n g t h d i s t r i b u t i o n due t o v i b r a t i o n a l entropy o f t h e d i s l o c a t i o n s and c l u s t e r i n g o f t h e p o i n t d e f e c t s .

The removal o f these two d i f f i c u l t i e s l e d t o a good agreement between t h e data of t h e two frequency ranges wi5h respect t o t h e p i n n i n g behavior. Concerning t h e temperature dependence, A L was found t o have t h e same values i n b o t h ranges which s t r o n g l y increased w i t h temperature. Concerning t h e drag constant B, howev

₉

obtained ( A and L a r e d e n s i t y and l o o p l e n g t h o f t h e d i s l o c a t i o n s ) . While i n t h e MHz-range t h e drag constant B increased approximately l i n e a r l y w i t h temperature, i t stayed constant i n t h e range between 40 and 350 K i n t h e kHz- range. This shows t h a t two d i f f e r e n t d i s l o c a t i o n drag mechanisms are a c t i n g i n t h i s frequency range. The reasons f o r t h i s behavior a r e not y e t completely c l a r i f i e d .