STRUCTURAL RELAXATION AND CRYSTALLIZATION OF FeB AND NiP METALLIC GLASSES FOLLOWED BY INTERNAL FRICTION AND MODULUS MEASUREMENTS

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STRUCTURAL RELAXATION AND

CRYSTALLIZATION OF FeB AND NiP METALLIC

GLASSES FOLLOWED BY INTERNAL FRICTION

AND MODULUS MEASUREMENTS

S. Kiss, G. Posgay, I. Harangozó, F. Kedves

To cite this version:

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STRUCTURAL R E L A X A T I O N AND C R Y S T A L L I Z A T I O N O F F e B AND N i p M E T A L L I C GLASSES FOLLOWED B Y I N T E R N A L F R I C T I O N AND MODULUS MEASUREMENTS

S. Kiss, G. Posgay, I.Z. Harangozd and F.J. Kedves

I n s t i t u t e for Applied Physics, Kossuth L. University, H-4010 Debrecen, Hungary

A b s t r a c t . - The dynamic e l a s t i c modulus and i n t e r n a l f r i c t i o n o f m e t a l l i c g l a s s e s w a s measured by a t o r s i o n a l pendulum w i t h low i n e r t i a l momentum and low e x t e r n a l damping.

The i n t e r n a l f r i c t i o n measured d u r i n g h e a t i n g i n c r e a s e s ra- p i d l y above 10o°C, and n e a r t h e c r y s t a l l i z a t i o n t e m p e r a t u r e i t

d e c r e a s e s s u d d e n l y , A t t h e same time a modulus jump i n one o r two s t e p s w a s f o u n d d u r i n g c r y s t a l l i z a t i o n i n a narrow tempera- t u r e range. I s o t h e r m a l measurements i n t h e c r y s t a l l i z a t i o n range show t h a t an i n c u b a t i o n t i m e i s needed and t h e v e l o c i t y of t h i s p r o c e s s depends on t e m p e r a t u r e as w e l l . A l a r g e c o n t i n u o u s i n - c r e a s e i n t h e dynamic e l a s t i c modulus w a s o b s e r v e d f a r below t h e c r y s t a l l i z a t i o n t e m p e r a t u r e i n a wide t e m p e r a t u r e r a n g e above 1 0 0 ~ ~ . T h i s i s p r o b a b l y c a u s e d by a s t r u c t u r a l r e l a x a t i o n pro- c e s s i n t h e amorphous s t a t e . No r e l a x a t i o n peak above room tem- p e r a t u r e w a s f o u n d n e i t h e r i n g l a s s y n o r i n c r y s t a l l i z e d s t a t e .

1. Experiment,- A new i n t e r n a l f r i c t i o n /i.f./ a p p a r a t u s w i t h low i n e r t i a momentum w a s c o n s t r u c t e d i n o r d e r t o measure t h e t h i n m e t a l - l i c g l a s s s a m p l e s h a v i n g i n t e r n a l s t r e s s e s t o o i n t h e f r e q u e n c y r a n g e of t o r s i o n a l v i b r a t i o n s of 0.1

-

1 He. The t o r s i o n a l pendulum i s b u i l t i n t o vacuum v e s s e l u n d e r p r e s s u r e of 1 0 - ~ ~ a , a n d t h e tempera- t u r e s c a n be v a r i e d by means of a n i n t e r n a l f u r n a c e up t o 600°c. To a v o i d t h e e l e t c r o d y n a m i c a t t e n u a t i o n of t h e i n d u c t i o n d e t e c t o r t h e a m p l i t u d e of v i b r a t i o n was i n d i c a t e d by a Sfram t y p e l i g h t f o l l o w i n g g a l v a n o m e t e r u s i n g t h e r e f l e c t e d l a s e r l i g h t f r o m t h e m i r r o r mounted o n t o t h e ~ e n d u l u n .

The NiP samples of 19.4 a t % P c o n t e n t were produced by an e l e c t r o - l e s s d e p o s i t i o n t e c h n i q u e a n d t h e specimens were c u t from a 40 um

_/

t h i c k s h e e t . The FeB samples of 1 7 a n d 20 at%B c o n t e n t were made by m e l t quenching t e c h n i q u e . The specimens were a b o u t 30,um t h i c k , 1 mm wide a n d a b o u t 30-50 mm long.

2. R e s u l t s and d i s c u s s i o n o - The i . f . and dynamic modulus /d.m./ s p e c t r a and t h e k i n e t i c ke'nmiour had a c o u p l e of s i m i l a r f e a t u r e s

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CS-530 JOURNAL DE PHYSIQUE

The i n t e r n a l

Fig. 1:

a t t enua-

Fig. 3:

Temperature dependence of dynamic modulus and i n t e r n a l f r i c t i o n of d i f f e r e n t amorphous a l l o y s .

t i o n of t h e m a t e r i a l s i n amorphous c o n d i t i o n a t room t e m p e r a t u r e /RT/

and a t h i g h e r t e m p e r a t u r e s i s c o n s i d e r a b l y h i g h e r t h e n i n c r y s t a l l i n e s t a t e . The i . f . of FeB m a t e r i a l s a t RT was always between 40 and

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l a t i v e l y low t e m p e r a t u r e s /at a b o u t 10oOc/ and d,m. i n c r e a s e s d i f f e - r e n t l y . D i f f e r e n c e s i n t h e b e h a v i o u r of v a r i o u s s a m p l e s b e g i n o n l y 1 0 0 ' ~ below t h e c r y s t a l l i z a t i o n t e m p e r a t u r e /Tx/ but t h e y have s i m i -

l a r b e h a v i o u r s t o o s i n c e i n t h i s r a n g e t h e r a p i d i n c r e a s e of i . f . c e a s e s and t h e d.m. h a s a l s o d e c r e a s i n g tendency. A t Tx i n a l l c a s e s t h e d,m. jumps up a b r u p t l y and t h e i . f . d e c r e a s e s s i g n i f i c a n t l y . A t h i g h e r t e m p e r a t u r e s t h e common b e h a v i o u r w a s f o u n d : t h e d.m. d e c r e a - s e s t h e i.f, i n c r e a s e s a p p r o x i m a t e l y e x p o n e n t i a l l y . The i . f . a n d d . 1 ~ s p e c t r a i n c r y s t a l l i n e s t a t e a r e smooth, t h e i . f . r u n s always below a n d t h e d.m. above t h e c u r v e s of t h e amorphous c o n d i t i o n . The d.m. of c r y s t a l l i n e s t a t e a t RP i s a t l e a s t 30-40% h i g h e r than t h a t of amorphous b u t one can f i n d much h i g h e r d i f f e r e n c e s t o o .

The s t r o n g i n c r e a s e i n d.m. and d e c r e a s e i n i . f . c a u s e d by c r y s - f a l l i z a t i o n a p p e a r i n t h e FeB m e t a l l i c g l a s s e s f o r b o t h composition. The c r y s t a l l i z a t i o n of Fe80B20 t a k e s p l a c e i n one s t e p between 400 and 4 2 0 ' ~ f o r s g i v e n /2OC/min/ h e a t i n g r a t e . The Feg3E17 samples have two c r y s t a l l i z a t i o n s t e p s between 380 and 4 4 0 ' ~ . The amount of i n c r e a s e i n d.m. i s 15% i n t h e f i r s t s t e p up t o a b o u t 4 0 0 ' ~ a n d f u r - t h e r 40% i n t h e s e c o n d one, The i . f . d e c r e a s e s i n one o r two s t e p s f r o m 600

x

1om4

t o a b o u t 300

x

10-~. It i s known t h a t t h e r e i s a two

s t e p c r y s t a l l i z a t i o n i n PeB h y p o e u t e c t i c a l l o y s , when a t f i r s t &-Fe t h e n Fe3B p r e c i p i t a t e s , I n c a s e of h i g h e r B c o n t e n t one can e x p e c t t h e p r e c i p i t a t i o n of t h e two c r y s t a l l i n e phase i n a s i n g l e s t e p . The c o m p o s i t i o n of FeB3B17 l i e s n e a r t o t h e e u t e c t i c one so w i t h r e s p e c t t o Tx t o o o u r r e s u l t s a r e i n good agreement w i t h p r e v i o u s d a t a ob- t a i n e d by means of d i f f e r e n t methods [2,3,4].

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C5-532 JOURNAL DE PHYSIQUE completed w i t h i n t i m e i n t e r v a l s i n d i c a t e d i n t h i s f i g u r e , T h i s i s c o n f i r m e d by t h e f a c t t h a t f u r t h e r h e a t t r e a t m e n t s at h i g h e r tempera- t u r e s c a u s e d o n l y s e v e r a l p e r c e n t i n c r e a s e s i n t h e d.m, The amount F i g . 4: C r y s t a l l i z a t i o n k i n e t i c s f o l l o w e d by d.m. measurement of Fe80B20. 1 ₃₆_C_'₅ 1 1. of d.1~~. in c r e a s e / a b o u t 35%/ a g r e e s w e l l w i t h t h o s e f o u n d d u r i n g con- t i n u o u s h e a t i n g and t h e t i m e needed f o r c r y s t a l l i z a t i o n i s a l s o t h e same as was o b s e r v e d u s i n g r e s i s t a n c e measurements /6],

The r a t e of c r y s t a l l i z a t i o n i n c r e a s e s on t h e c u r v e b e l o n g i n g t o 3 6 5 ' ~ above 45 min f r o m t h e b e g i n n i n g /Pig. 4/. The same phenomena can be s e e n more e x p r e s s e d i n t h e c a s e of BiP samples where t h i s change /Fig. 5b/ o c c u r e d a f t e r 1 h r a t 2 8 0 ' ~ and a f t e r 2 hrs a t 2 7 & ~ ,

Fig. 5: S t r u c t u r a l r e l a x a - t i o n /a/ and i n c u b a t i o n pe- r i o d of c r y s t a l l i z a t i o n /b/

T h i s shows t h a t b e f o r e c r y s t a l l i z a t i o n a c e r t a i n time of i n c u b a t i o n i s needed which i s a l r e a d y known from c a l o r i m e t r i c measurements

[7].

The i.f. i n b o t h t y p e s of m a t e r i a l s d e c r e a s e d a t t h e beginning of c r y s t a l l i z a t i o n q u i c k l y enougho A f t e r t h e i n c u b a t i o n time e l a p s e d t h e i . f . i n c r e a s e d s l i g h t l y o r t h e r a t e of d e c r e a s e d i m i n i s h e d what

can be i n t e r p r e t e d by t h e f a c t t h a t t h e p r o c e s s of c r y s t a l l i z a t i o n i t s e l f g i v e s a c o n t r i b u t i o n t o t h e d i s s i p a t i o n .

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and cooling down were made with increasing temperatures. The results gained on NiP are summarized in Fig.

6. It

can be seen that a holding

Fig.

6:

Effect of subsequent heat treatments on the spectra of NiBOQ6

.

0

for one hour at 50 C causes and increase in d.m. and decrease in i.f. and this effect is more and more significant at temperatwes

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C5-534 JOURNAL DE PHYSIQUE

can cause d.m. increase and i.f. decrease. During intervals of con- stant temperatures the d.m. increased approximating the equilibrium value and the i.f. decreased expoenntially /Fig. 5a/. It can be seen in Fig. 6, that the d.m. increased 75% from the RT value up to start- ing the crystallization at 280'~ and during this process further 55% increase was observed. We can conclude inspecting the i.f. and d.m. curves of Fig. 6, that no relaxation peak occured within the temperature range investigated for the studied materials in the amorphous and different crystalline state.

References

[l] R. Maddin,

IT.

Masumoto; Mater. Sci. Eng.

2,

153 /1972/

[ 2 ] J. L, Walter, S.F. Bartram, I. Mella; Mater, Sci.Eng. 36,193 /1978/ 131 J.L. Walter; Mater. Sci. Eng. 39, 95 /1979/

[4] L. Potecky,

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Karel, E, Kisdi-Kosz6,

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l!Tov&, S. Longauer;

Hung. Acad. Sci., Central Research Institute for Physics

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106.

[5]

A.

Czir&i, B, Fogarassy,

I,

Bakonyi,

K.

ITompa,

T.

Bagi, Z. He-

gediis; Hung. Acad. Sci., Central Research Institute for Physics

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161 J, T6th; Hung. Acad. Sci., Central Research Institute for Phy- sics

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1978

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