DEVIATION OF STRUCTURAL RELAXATION FROM THE PURE DEBYE CHARACTER IN Fe40Ni40B20 METALLIC GLASS

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Submitted on 1 Jan 1983

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DEVIATION OF STRUCTURAL RELAXATION FROM THE PURE DEBYE CHARACTER IN

Fe40Ni40B20 METALLIC GLASS

R. Kamel, N. Gobran, S. Saleh, B. Hanna

To cite this version:

R. Kamel, N. Gobran, S. Saleh, B. Hanna. DEVIATION OF STRUCTURAL RELAXATION FROM

THE PURE DEBYE CHARACTER IN Fe40Ni40B20 METALLIC GLASS. Journal de Physique Col-

loques, 1983, 44 (C9), pp.C9-105-C9-109. �10.1051/jphyscol:1983910�. �jpa-00223332�

JOURNAL DE PHY SlQUE

Colloque C9, suppl6ment au n 0 1 2 , Tome 44, d k e m b r e 1983 page C9-105

D E V I A T I O N OF STRUCTURAL RELAXATION FROM THE PURE DEBYE CHARACTER I N F e * O N i 4 Q B 2 0 METALLIC GLASS

R. Kamel, N . K . Gobran, S . S a l e h and B . F . Hanna

Physics Department, Faculty of Science, University o f Cairo, Giza, Egypt

~ k s u m 6

-

La r e l a x a t i o n s t r u c t u r e l l e p a r r d a r r a n g e r n e n t t o p o l o g i q u e e t chimique A c o u r t e p o r t e ' e a 6te' examinde d a n s l e v e r r e m k t a l l i q u e Fe40Ni40%0, emplo- y a n t l e s m e s u r e s du module d e Young, l a f r i c t i o n i n t e r n e e t l e p e r t e d e l t 6 n e r g i e magn&tique. On a tltilise' l a t e c h n i q u e d e l a v i b r a t i o n b a s s e f r & - u e n c e s u r l a m e l l e a i n s i que l a me/thode d e l a b o u c l e d ' h y s t & r C s i s , A p a r t i r du v i r a g e d e l a fre'quence d e s bandes d l a b s o r p t i o n d i v e r s e s t e m p & a t u r e s a v a n t l a c r i s t a l l i s a t i o n , on a & v a l u e ' r e s p e c t i v e m e n t

A

0.6 e t 1.7 e l e c t r o n

-

v o l t s 1 ' 6 n e r g i e d ' a c t i v a t i o n d e r g a r r a n g e m e n t t o p o l o g i q u e e t chimique 2 c o u r t e p o r t g e . L ' a n a l y s e t h e b r i q u e a m o n t r g q u e l f o r d r e

2

c o u r t e p o r t g e q u i s l e f f e c t u e d a n s l e s v e r r e s m d t a l l i q u e s se c a r a c t g r i s e p a r un temps d e r e l a x a - t i o n c o u r t mais a y a n t u n e d i s t r i b u t i o n d ' e n e r g i e d ' a c t i v a t i o n s o u s forme d e queue a s y m 6 t r i q u e d a n s l e s p e c t r e d e r e l a x a t i o n b a s s e s t e r n p & r a t u r e s . Un modele s e b a s a n t s u r l a q u a n t i f i c a t i o n du volume l i b r e d a n s l a s t r u c t u r e d t a l l i q u e amorphe a Lt6 & l a b o r & e t p r g s e n t d . I1 a &te/ employd pour l 1 i n t e r - p r 6 t a t i o n d e s v a l e u r s o b t e n u e s a i n s i que l a d i s t r i b u t i o n d e s e n e r g i e s d t a c t i - v a t i o n pour l e s d e u x t y p e s d e r e a r r a n g e m e n t c o u r t e p o r t d e .

A b s t r a c t

-

S t r u c t u r a l r e l a x a t i o n by t o p o l o g i c a l and c h e m i c a l s h o r t - r a n g e o r d e r (TSRO and CSRO) i n F e 4 0 N j 4 0 B 2 0 m e t a l l i c g l a s s was i n v e s t i g a t e d u s i n g Young's modulus, i n t e r n a l f r i c t i o n and m a g n e t i c e n e r g y l o s s measurements. The v i b r a t i o n r e e d t e c h n i q u e i n t h e low

-

f r e q u e n c y r a n g e and t h e h y s t e r e s i s l o o p method were a d o p t e d . From t h e f r e q u e n c y s h i f t s of t h e a b s o r p t i o n bands o b s e r - ved a t d i f f e r e n t t e m p e r a t u r e s below c r y s t a l l i z a t i o n , a c t i v a t i o n e n e r g i e s of 0.6 and 1 . 7 e V were c a l c u l a t e d f o r TSRO and C S R 0 , r e s p e c t i v e l y . T h e o r e t i c a l a n a l y s i s r e v e a l e d t h a t s h o r t

-

r a n g e o r d e r t a k i n g p l a c e i n m e t a l l i c g l a s s e s was c h a r a t e r i z e d by a s i n g l e r e l a x a t i o n t i m e , b u t w i t h a d i s t r i b u t i o n of ac- t i v a t i o n e n e r g i e s showing i t s e l f a s an asymmetric t a i l i n t h e r e l a x a t i o n s p e c t r u m a t lower t e m p e r a t u r e s . A model based on t h e q u a n t i z a t i o n of f r e e volume i n t h e amorphous m e t a l l i c s t r u c t u r e was p r e s e n t e d and was u s e d t o i n - t e r p r e t t h e v a l u e s and t h e d i s t r i b u t i o n of a c t i v a t i o n e n e r g i e s f o r b o t h t y p e s of s h o r t

-

r a n g e o r d e r .

I n t r o d u c t i o n

-

I t i s p r e s e n t l y w e l l known 11-41 t h a t s t r u c t u r a l r e l a x a t i o n s d o e x i s t i n m e t a l l i c g l a s s e s b e f o r e t h e o n s e t of c r y s t a l l i z a t i o n . The r e l a x a t i o n i n v o l v i n g l o c a l a t o m i c s h i f t s t h a t do n o t d i s c r i m i n a t e between d i f f e r e n t t y p e s of constituent atoms g i v e s r i s e t o t o p o l o g i c a l s h o r t

-

r a n g e o r d e r (TSRO). Chemical r e l a x a t i o n o c c u r r i n g a t r e l a t i v e l y h i g h e r t e m p e r a t u r e s i n v o l v e s a t o m i c bonding of s i m i l a r m a g n e t i c atoms, and i s u s u a l l y termed c h e m i c a l s h o r t

-

r a n g e o r d e r (csRO). Mechanical p r o p e r t i e s s u c h a s i n t e r n a l f r i c t i o n , Q-l, and Young's modulus, E

,

w e r e f o u n d t o be more sen- s i t i v e t o r e l a x a t i o n by TSRO 1 5 1 , whereas m a g n e t i c p r o p e r t i e s were u s u a l l y t a k e n t o t r a c e CSRO 161. Due t o t h e amorphous s t r u c t u r e of m e t a l l i c g l a s s e s and t h e random d i s t r i b u t i o n of f r e e volume i n t h e m a t r i x , i t i s t h o u g h t t h a t t h e u n i t r e l a x a t i o n a l e l e m e n t m i g h t change s l i g h t l y from p l a c e t o p l a c e . The aim of t h e p r e s e n t work i s t o t e s t t h e d e v i a t i o n of t h e o v e r a l l r e l a x a t i o n from t h e p u r e Debye r e l a x a t i o n , and t o f i n d o u t w h e t h e r t h e r e i s a d i s t r i b u t i o n i n a c t i v a t i o n e n e r g y a n d / o r r e l a x a t i o n time.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1983910

C9-106 JOURNAL DE PHYSIQUE

E x p e r i m e n t a l

-

F l e x u r a l v i b r a t i o n s of s h o r t r i b b o n s of Fe40

NkO

B ~ ~ ( * ) were e l e c t r o s t a t i c a l l y t r a c e d by a m i c r o

-

v i b r a t i o n d e t e c t o r 171. The i n t e r n a l f r i c t i o n was d e t e r m i n e d by t h e r e s o n a n c e c u r v e m e t h o d t o an a c t u r a c y of 4 % . Changes i n t h e e l a s t i c modulus of t h e o r d e r o f 0.005 c o u l d be d e t e r m i n e d from t h e c h a n g e i n t h e n a t u r a l f r e q u e n c y of t h e r i b b o n . The m a g n e t i c e n e r g y l o s s was d e t e r m i n e d from t h e h y s t e r e s i s l o o p a r e a r e c o r d e d by t h e o s c i l l o s c o p e method.

R e s u l t s

-

(i) E ~ ! $ ~ ! ~ ~ - ~ E ! ~ ~ ! ~ E - Z ~ ~ - Y O U - E S ~ B - I ? O ! U ~ U Z

The t e m p e r a t u r e dependence of i n t e r n a l f r i c t i o n , Q-l, and Young's modulus, E

,

i n d i - c a t e d a r e l a x a t i o n a l b e h a v i o u r a t t e m p e r a t u r e s s l i g h t l y above 400 K showing i t s e l f a s a peak i n Q-I, a s s o c i a t e d w i t h a d r o p i n E . The t e m p e r a t u r e s a t which t h e r e l a x a - t i o n was f u l l y o p e r a t i v e was found t o s h i f t t o h i g h e r v a l u e s a s t h e v i b r a t i o n f r e q - uency i n c r e a s e d ( F i g . 1 ) . The r e l a t i o n between r e l a x a t i o n t e m p e r a t u r e and t h e c o r r e s - ponding v i b r a t i o n f r e q u e n c y ( F i g . 2 ) y i e l d e d an e n e r g y of 0.6 eV a c t i v a t i n g t h e r e - l a x a t i o n p r o c e s s i n a c t i o n .

(11)

Magr$_t;r-energr-lo~:

The m a g n e t i c e n e r g y l o s s , t a n 6 , of t h e t e s t sample was measured a t d i f f e r e n t temper- a t u r e s up t o t h e c r y s t a l l i z a t i o n . A c h a r a c t e r i s t i c peak i n t a n 6 superimposed t h e broad peak e f f e c t e d by c r y s t a l l i z a t i o n . T h i s proved t o have a r e l a x a t i o n o r i g i n a s e v i d e n c e d by t h e o b s e r v e d s h i f t t o h i g h e r t e m p e r a t u r e s a s t h e f i e l d f r e q u e n c y i n - c r e a s e d ( F i g . 3 ) . The f r e q u e n c y s h i f t y i e l d e d a n a c t i v a t i o n e n e r g y of 1.7 eV.

D i s c u s s i o n

-

( i ) A n a l y s i s of t h e two r e l a x a t i o n peaks

- ...

I n view of t h e random c l o s e packed s t r u c t u r e of t h e amorphous t e s t s a m p l e , s t r u c t u - r a l r e l a x a t i o n p r o c e s s e s seemed t o o c c u r w i t h a s p e c t r u m i n a c t i v a t i o n e n e r g i e s and o r r e l a x a t i o n t i m e s . To i n t e r p r e t t h e p r e s e n t o b s e r v a t i o n s , we f i r s t assume t h a t t h e a c t i n g p r o c e s s e s a r e t h e r m a l l y a c t i v a t e d w i t h a s i n g l e r e l a x a t i o n t i m e . The norma- l i z e d Q-l c a n t h u s be e x p r e s s e d i n t h e form / 8 / ,

- .

Q-l/ Q,' = s e c h ( - H / k ) ( T i L

-

T - I )

, . ....

^{( 1 )}

where Q - l i s t h e peak v a l u e of i n t e r n a l f r i c t i o n o c c u r r i n g a t t e m p e r a t u r e , TM. Accor- d i n g l y , M a p l o t of

Q-4

Qhl v e r s u s (TG'

-

T-l ) would y i e l d a symmetric c u r v e a b o u t T = TM, f o r a s i n g l e r e l a x a t i o n p r o c e s s . S u b s t i t u t i n g i n e q u a t i o n ( I ) by t h e a c t i v a - t i o n e n e r g y , H = 0.6 e V , h e r e deduced f o r TSRO

,

v a l u e s of

Q-4

Qkl were c a l c u l a t e d and t h e d a s h e d c u r v e i n F i g . 4 r e s u l t e d . It c o u l d be s e e n from F i g . 4 t h a t t h e ex- p e r i m e n t a l d a t a f i t t e d t h e t h e o r e t i c a l c u r v e a t r e l a t i v e l y h i g h t e m p e r a t u r e s w h i l e i t showed a l a r g e low t e m p e r a t u r e asymmetry. T h i s asymmetric t a i l of t h e r e l a x a t i o n s p e c t r u m was p r e v i o u s l y o b s e r v e d 1 9 , 1 0 1 and was commonly c o n s i d e r e d a n i n t r i n s i c p r o p e r t y of t h e amorphous s t a t e . Applying t h e same a n a l y s i s t o t h e a b s o r p t i o n band d e t e c t e d m a g n e t i c a l l y , a s i m i l a r asymmetric b e h a v i o u r of t h e r e l a x a t i o n band was found ( F i g . 5 ) . Although t h e o r i g i n of t h i s r e l a x a t i o n by CSRO i s d i f f e r e n t from t h a t d e t e c t e d m e c h a n i c a l l y , y e t t h e asymmetric t a i l o b s e r v e d i n b o t h r e l a x a t i o n s p e c - t r a i m p l i e d t h a t t h e a c t i v a t i o n e n e r g y f o r s h o r t - r a n g e o r d e r f l u c t u a t e s from p l a c e t o p l a c e w i t h i n t h e m a t r i x d e s p i t e t h e u n i q u e n e s s of t h e r e l a x a t i o n t i m e .

(

f i )

R::$t("'3:s-:y-TsRc

C o n s i d e r i n g t h e m i c r o s c o p i c model f o r a t o m i c t i l t i n g p r e v i o u s l y p r e s e n t e d by t h e au- t h o r s

1111,

which i s based on a q u a n t i z a t i o n of f r e e volume i n m e t a l l i c g l a s s e s , t h e l a s t c o n c l u s i o n c o u l d be i n t e r p r e t e d a s f o l l o w s . The random d i s t r i b u t i o n of t h e f r e e

(*"I

The s a m p l e s were r e c e i v e d from Max-Planck i n s t i t u t f i i r metallforschung,Stuttgart,

West Germany.

Temperature T ( K )

5

- ..-

4

c :

F i g . 1

-

T e m p e r a t u r e dependence of t h e modulus F i g . 2

-

N a t u r a l f r e q u e n c y of t h e d e f e c t , E / E u , and t h e n o r m a l i z e d i n t e r n a l f r i c - sample v e r s u s t h e i n v e r s e tempera- t i o n peak a f t e r b e i n g removed from i t s back- t u r e a t which t h e r e l a x a t i o n i s g r o u n d , f o r Feho N i 4 0 BZ0 m e t a l l i c g l a s s . f u l l y o p e r a t i v e .

Internal frtctlon

.

^0-'

0 Young's modulus.E

-

I I

2 2

\

2 4

volume o v e r t h e whole m a t r i x i m p l i e s t h a t t h e quantum of v o i d , termed "vacy", m i g h t n o t b e e q u a l l y a v a i l a b l e a t d i f f e r e n t l o c a t i o n s . Hence, a t o m i c t i l t i n g would r e q u i r e an a c t i v a t i o n e n e r g y e q u i v a l e n t t o t h e m i g r a t i o n e n e r g y of a vacy when it a c t u a l l y e x i s t s . However, i n p l a c e s w h e r e i t i s n o t a v a i l a b l e , a t o m i c t i l t i n g would r e q u i r e an e n e r g y f o r vacy f o r m a t i o n a s w e l l a s m i g r a t i o n . The p r e s e n t l y o b s e r v e d e n e r g y a c t i v a t i n g TSRO, namely, 0.6 e V , t h u s f l u c t u a t e from a lower l i m i t i n g e n e r g y f o r vacy m i g r a t i o n t o an u p p e r l i m i t o f t h e sum of f o r m a t i o n and m i g r a t i o n e n e r g i e s of t h i s quantum of v o i d . I t s h o u l d be n o t e d t h a t i n c o n t r a s t w i t h t h e c a s e of c r y s t a l - l i n e s o l i d s , t h e vacy f o r m a t i o n p r o c e s s i n an amorphous s t r u c t u r e i s r a t h e r u n i d e n - t i £ i a b l e .

1000 / T ( K-')

)

E ~ ~ ~ i ( a t i ~ > - ~ y - $ ~ E ~

Bonding of t h e s i m i l a r f e r r o m a g n e t i c atoms ( F e - F e , N i - Ni) i n t h e m e t a l l i c g l a s s Fe40 Ni40 B20 seemed t o form t h e o r i g i n of CSRO. Here a l s o , t h e r e l a x a t i o n mecha- nism was c o n t r o l l e d by f r e e volume m i g r a t i o n a s s o c i a t e d w i t h a t o m i c t i l t i n g and s h i f t i n g . T h i s was c o n f i r m e d by t h e s u g g e s t i o n of Chen and Egami / 6 / t h a t t h e k i n e - t i c s of t h e CSRO a r e d e t e r m i n e d by t h e a v a i l a b i l i t y of t h e f r e e volume i n t h e n e a r b y l o c a l i t y . The h i g h a c t i v a t i o n e n e r g y (1.7 eV) o b s e r v e d f o r t h e CSRO m i g h t be i n f e r r e d t o n e c e s s a r y a t o m i c d i s p l a c e m e n t s t h a t b r i n g t o g e t h e r s i m i l a r f e r r o m a g n e t i c atoms.

The f l u c t u a t i o n of t h i s v a l u e from p l a c e t o p l a c e c o u l d be a l s o e x p l a i n e d i n t e r m s of t h e p r e s e n c e of f r e e volume i n d i f f e r e n t amounts v a r y i n g from p l a c e t o p l a c e , t h u s m o d i f y i n g t h e e n e r g y b a r r i e r f o r a t o m i c d i s p l a c e m e n t s . The d e c r e a s e i n t h e c h e m i c a l p o t e n t i a l by bonding two s i m i l a r m a g n e t i c atoms t o g e t h e r forms t h e m o t i v e f o r c e f o r t h e m i g r a t i o n of v a c i e s . A u n i t m i g r a t i o n of a quantum of v o i d m i g h t n o t be s u f f i c i e n t t o b r i n g a b o u t t h i s bonding p r o c e s s . S e v e r a l vacy jumps m i g h t be need- ed t o p r o d u c e one r e q u i r e d l i n k , i . e . , one m a g n e t i c d i p o l e . On a c c o u n t of p r e v i o u s l y c a l c u l a t e d e n e r g y f o r TSRO (0.6 eV) which i s a r e s u l t of a s i n g l e vacy s h i f t , one

JOURNAL

DE

_PHYSIQUE

Temperature T (K)

F i g . 3

-

T e m p e r a t u r e dependence of m a g n e t i c e n e r g y l o s s , t a n 6 , f o r Feb0

m e t a l l i c g l a s s . Ni40 B20

F i g . 4

-

I n t e r n a l f r i c t i o n v e r s u s t h e i n v e r s e F i g . 5

-

Magnetic e n e r g y l o s s v e r s u s t e m p e r a t u r e f o r t h e f i r s t r e l a x a t i o n p r o c e s s . t h e i n v e r s e t e m p e r a t u r e f o r t h e s e - The d a s h e d c u r v e r e p r e s e n t s a s i n g l e r e l a x a - cond r e l a x a t i o n p r o c e s s . The dashed t i o n of a c t i v a t i o n e n e r g y , H = 0.6 eV. c u r v e r e p r e s e n t s a s i n g l e r e l a x a t i o n

of a c t i v a t i o n e n e r g y , H = 1 . 7 eV.

1.0

0.9 E

rO c 0.8

.

u rO _u

=

^0.7

0.6

0.5.

would e s t i m a t e t h a t t h e u n i t r e l a x a t i o n p r o c e s s of CSRO would r e q u i r e , o n t h e a v e r a g e , t h r e e vacy s h i f t s n e e d i n g a b o u t , 1 . 7 eV.

!

!

.

_o ^f _f

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_r ^2.0 _{3.5 kHz} ^kHz

-

,vrrT%..

^{x f : 6.02 kHz}

O /'

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X I

-

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^{! A.}

x

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^{! f}

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-

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I !

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,

! ^! _! ^"s

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,

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-1.5 -1.0 -0.5 0 0.5 1.0 1.5

R e f e r e n c e s

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1- CHEN H.S. and COLEMAN E . , Appl. Phys. L e t t .

28

( 1 9 7 6 ) 2 4 5 . 2.. EGAMI T . , J . Mater. S c i .

12

( 1 9 7 8 ) 2587

.

3. TAUB A.I. and SPAEPEN F., G e n e r a l E l e c t r i c Company, S c h e n e c t a d y , N.Y., 8 0 CRD 1 8 7 ( 1 9 8 0 ) .

4. CHEN H.S., J . Appl. Phys.

49

( 1 9 7 8 ) 3 2 8 9 . 5. EGAMI T., Mat. Res. B u l l . 1 3 ( 1 9 7 8 ) 557

_- .

6. CHEN Y.

-

^N. and EGAMI T . , J. Appl. Phys.

50

( 1 9 7 9 ) 7 6 1 5 .

7. YOUSEF Y.L., EL-SALAM E.A., SAADELDIN M.M. and KHALIL S.M., J. Phys. E.

3

(1970) 829

.

8. BARMATZ M. and CHEN H.S., Phys. Rev. B

9

( 1 9 7 4 ) 4 0 7 3 . 9. BARMATZ M. and GOLDING B., Phys. Rev. B

9

( 1 9 7 4 ) 3 0 6 4 .

10. COPLEY G.J. and OAKLEY D.R., Phys. Chem. G l a s s e s

9

( 1 9 6 8 ) 1 4 1 .

11. KAMEL R . , GOBRAN N.K., SALEH S. and HANNA B.F., J. P h y s i q u e

42

^{(1981) C 5}

-

5 0 5 .