REVERSIBLE AND IRREVERSIBLE ORDERING PROCESSES AND MECHANICAL BEHAVIOUR IN FeNiMoB AMORPHOUS ALLOYS

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REVERSIBLE AND IRREVERSIBLE ORDERING

PROCESSES AND MECHANICAL BEHAVIOUR IN

FeNiMoB AMORPHOUS ALLOYS

P. Allia, E. Bonetti, E. Evangelista, F. Vinai

To cite this version:

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JOURNAL DE PHYSIQUE

Colloque CIO, supplément au n o 12, Tome 46, décembre 1985 page CIO-485

REVERSIBLE AND IRREVERSIBLEORDERING PROCESSES AND MECHANICAL BEHAVIOUR I N FeNiMoB AMORPHOUS ALLOYS

P.

ALLIA, E. BONETTI', E. EVANGELISTA' AND F. VINAI

Istituto Elettrotecnico Nazionale "G. Ferraris", GNSM,Corso

M.

D ' Azeglio 4 2 , Torino, Italy

'Dipartimento

di

Fisica, Università d i Bologna, CISM-GNSM, Via Irnerio 46, Bologna, Italy

Résumé

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On a mésuré des paramétres anélastiques e t mechaniques

sur

des ru- m i n o r p h e s d'un a l l i a g e FeNiMoB, obtenus avec des d i f f é r e n t e s v i t e s s e s de trempe. On observe des modifications reversibles e t i r r é v e r s i b l e s des parame- t r e s anélastiques. La resistance e t l a d u c t i l i t é montrent des variations re- l i é s aux des changements de module qui ont é t é observés bien au dessous de l a température de c r i s t a l l i s a t i o n . I l p a r a î t que toutes ces quantites soient in- influencés par l e d i f f e r e n t condition d'amorphicite des materiaux.

Abstract

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Anelastic and mechanical parameters have been measured on amorphas m r i b b o n s obtained with d i f f e r e n t quenching r a t e s . Reversible and i r r e - v e r s i b l e changes of the a n e l a s t i c parameters have been observed. Strength and d u c t i l i t y show variations connected with the modulus changes observed, well below t h e c r y s t a l l i z a t i o n temperature. Al1 these q u a n t i t i e s seem t o be i n f l u - enced by t h e d i f f e r e n t degree of amorphicity.

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IHTRODUCTION

A t present there i s c l e a r evidence t h a t relaxation processes associated t o structural relaxation i n amorphous alloys cannot be simply described in terms of the a l l o y chemical composition, but t h a t these depend also on the quenching r a t e a t which the alloys a r e produced. Many physical properties, i n f a c t , a r e noticeably affected by t h e amorphicity degree such as a n e l a s t i c i t y / 1 / , Curie temperature /2/, permeability a f t e r - e f f e c t /4/ and d u c t i l i t y .

This paper deals with a comparison between the behaviour of a n e l a s t i c and mechanical parameters made on amorphous ribbons of the sarne nominal composition, obtained with d i f f e r e n t quenching r a t e s . P a r t i c u l a r a t t e n t i o n was paid t o the study of the i n f l u - ence of t h e f r e e volume content frozen i n the as-cast alloys on both the reversible and i r r e v e r s i b l e components of the a n e l a s t i c behaviour observed, as well as on t h e s t r e s s and s t r a i n a t f r a c t u r e . In addition, measurements were made on t h e influence of magnetoelastic damping components on the a n e l a s t i c spectra.

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EXPERIMEFlTAL

The measurements were made on ribbons of nominal composition Fe40rii38!~1oqB18,obtained

a t d i f f e r e n t quenching r a t e s by s i n g l e r o l l e r melt spinning i n a i r , by varying the rol l e r speed. Ho s i g n i f i c a n t compositional s h i f t was observed in the d i f f e n t ribbons. Interna1 f r i c t i o n 9-1 and dynamic Young modulus Eld were obtained by means of a f r e - quency modulation detection technique i n the 102

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103 Hz range, from the decay of the e l e c t r o s t a t i c a l l y excited flexural vibrations of ribbons

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1

cm long, c a n t i l e v e r mounted under a 10-2 Pa vacuum.

To evaluate t h e influence of the magnetoelastic component on both damping and modu- l u s , some measurements were carried out by surrounding the specimens inside tha ap- ratus with a coi1 so as t o e i t h e r bring the sample t o saturation or perform a conven- tional a.c. dernagnetization.

The deformation t e s t s a t a constant s t r a i n r a t e of

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10-4 (s-1) were performed with

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C10-486 JOURNAL D E PHYSIQUE

an INSTRON type machine. Al1 thermal treatments on t h e as-cast specimens were p e r - formed i n s i t u b e f o r e each deformation t e s t . Four s e r i e s o f ribbons obtained a t d i f - f e r e n t r o l l e r speeds Vs, r e s p e c t i v e l y : 48 m/s (A), 40 m/s (B), 30 m/s (C) and 26 m/s

(O),

were examined. III

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RESULTS

F i g u r e 1 shows t y p i c a l Q-1 ( a ) and !Id ( b ) trends f o r specimens o f d i f f e r e n t s e r i e s d u r i n g isothermal measurements a t T = 450 K. The i n t e n s i t y v a r i a t i o n o f both quan- t i t i e s increases w i t h t h e quenching r a t e . These r e s u l t s a r e i n agreement w i t h Fld(T) and Q - I ( T ) s p e c t r a o b t a i n e d w i t h measurements a t 2 K/min h e a t i n g r a t e on t h e same r i b b o n s /1/. I n t h a t case a s t r o n g Md i n c r e a s e w i t h a p a r a l l e l Q-1 decrease was observed i n t h e f a s t quenched ribbons, i n t h e temperature range 400-500 K.

To e v a l u a t e t h e i n f l u e n c e o f t h e magnetoelastic component on t h e

Q-1

and Md t r e n d s some o f t h e measurements have been performed on m a g n e t i c a l l y s a t u r a t e d samples. F i g - u r e 2 r e p o r t s t h e dynamic modulus t r e n d i n s a t u r a t e d c o n d i t i o n s ~ - ) and i n zero f i e l d (--)during annealing o f t h e A and C s e r i e s specimens. I n b o t h cases t h e ??d values i n m a g n e t i c a l l y s a t u r a t e d c o n d i t i o n s a r e g r e a t e r than i n zero f i e l d and t h e d i f f e r e n c e tends t o reduce d u r i n g annealing.

R e v e r s i b l e v a r i a t i o n s o f t h e a n e l a s t i c parameters have been observed by c y c l i n g between two d i f f e r e n t temperatures a f t e r l o n g ageing t i m e (104-105 sec) a t t h e h i g h e r one. T y p i c a l trends f o r Q-1 and p1d f o r t h e s e r i e s A, C specimens are shown i n Fig. 3. The times f o r thermal s t a b i l i z a t i o n a t b o t h measurement temperatures were o f t h e o r d e r o f 250 sec.

The room temperature s t r e s s - s t r a i n r e l a t i o n observed a t f r a c t u r e ( o ~ vs EF) i n specimens o f d i f f e r e n t s e r i e s i s shown i n Fig. 4. Despite t h e s c a t t e r i n g o f t h e experimen- t a 1 d a t a an i n c r e a s e o f both of and ~f i s observed w i t h decreasing quenching r&e.

T y p i c a l values f o r of and ~f i n as-cast c o n d i t i o n s and a f t e r ageing treatments a r e r e p o r t e d i n Table 1.

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DISCUSSION

L e t us f i r s t c o n s i d e r t h e annealing e f f e c t s on t h e a n e l a s t i c parameters r e p o r t e d i n Fig. 1. The main e f f e c t i s t h e s t r o n g )Id i n c r e a s e (Q-1 decrease) observed on f a s t quenched ribbons, n o t p r e s e n t o r g r e a t l y reduced i n those s l o w l y quenched. As p r e v i - o u s l y p o i n t e d o u t , t h i s behaviour i s connected t o i r r e v e r s i b l e s t r u c t u r a l r e l a x a t i o n phenomena. The r e s u l t s r e p o r t e d i n Fig. 1 r e f e r t o as-cast samples. I n these f e r r q - magnetic specimens, below t h e C u r i e temperature (Tc

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620 K) t h e magnetoelastic e f f e c t s connected w i t h Bloch w a l l motion may c o n t r i b u t e s u b s t a n t i a l l y t o t h e Q-1 and Md measured. Strong increases o f t h e AE e f f e c t due t o i n t e r n a 1 s t r e s s r e l i e f by anneal- i n g has been observed by v a r i o u s authors /5,6/ on m a g n e t o s t r i c t i v e amorphous a l l o y s . As shown i n Fig. 2 t h e modulus values d u r i n g annealing i n a s a t u r a t i n g magnetic f i e l d a r e i n every case h i g h e r than those i n zero f i e l d . The d i f f e r e n c e , o f t h e o r d e r o f 2-4%: reduces somewhat d u r i n g annealing b u t t h e o v e r a l l t r e n d s o f t h e M d ( t ) curves remain s u b s t a n t i a l l y unchanged.

These r e s u l t s confirm t h a t t h e s t r o n g modulus increase observed i n t h e f a s t quenched specimens and almost absent i n those s l o w l y quenched i s e s s e n t i a l l y a n e l a s t i c and o r i g i n a t e s from s t r u c t u r a l r e l a x a t i o n probably caused by TSRO w i t h f r e e volumereduc- t i o n . A f u r t h e r i n s i g h t i n t o t h i s problem comes from t h e d a t a r e p o r t e d i n Table 1. These show t h a t A r i b b o n s s u b n i t t e d t o t h e same thermal treatments corresponding t o t h e isotherms g i v e n i n Fig. 1 show an increase o f UF and p o s s i b l y o f EF. Moreover, a f t e r annealing a t 400-450 K t h e and EF values o f t h e f a s t quenched specimens

(Table 1) gets c l o s e r t o those o f t h e as-cast s l o w l y quenched ribbons. I n

a d d i t i o n t h e r e s u l t s i n Fig. 4 a r e i n agreement w i t h r e c e n t measurements on deformed metal-glass w i r e s /7/, according t o which t h e specimens obtained a t t h e lower quendi- i n g r a t e s show h i g h e r OF values. Our r e s u l t s can reasonably be e x p l a i n e d i f i t i s as-

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times. I n Our case embrittlement e f f e c t s a r e observed on t h e s e r i e s A specimens f o l l w - i n g t h e s t r e n g t h i n c r e a s e a f t e r annealing a t h i g h e r temperature (T

>

540 K), whereas those obtained ' a t lower quenching r a t e ( s e r i e s C-D) show e m b r i t t l e m e n t a t l o w e r temperatures (T

<

470

K)

i n agreement w i t h r e s u l t s obtained on Cu46Zt-54 /9/ and on Fe40Wi40B20 /1 O / met-glasses. F i n a l l y t h e temperature c y c l i n g r e s u l t s (Fig. 3) i n d i - c a t e t h a t compositional o r d e r i n g processes i n d u c i n g Md v a r i a t i o n s can be d i s t i n - guished a l s o when superimposed t o s t r u c t u r a l r e l a x a t i o n e f f e c t s /Il/. It may be no- t i c e d t h a t i n t h e present measurements t h e specimens a r e n o t completely relaxed. The s l i g h t s h i f t between d a t a taken d u r i n g t h e f i r s t and t h e second c i c l e (open and f u l l c i r c l e s i n d i c a t e t h e simultaneous presence o f a small amount o f i r r e v e r s i b i l i t y , p r e c i s e l y r e l a t e d t o t h e r e s i d u a l e f f e c t o f s t r u c t u r a l r e l a x a t i o n t a k i n g p l a c e d u r - i n g t h e measurements. Our r e s u l t s seem t o i n d i c a t e t h a t t h e d i f f e r e n t quenching r a t e s produce d i f f e r e n t r e v e r s i b l e e f f e c t s ; t h e Fld v a r i a t i o n s a r e i n f a c t g r e a t e r by about a f a c t o r 2 i n t h e A specimens i n comparison w i t h t h e D specimens.

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CONCLUSIONS

The measurements c a r r i e d o u t on h i g h l y d i s o r d e r e d f a s t quenched ribbons show an i m -

portantmodulus increase o f a n e l a s t i c type, w i t h a p a r a l l e l i n c r e a s e i n t h e f r a c t u r e s t r e s s w e l l b e f o r e complete s t r u c t u r a l r e l a x a t i o n . T h i s i s probably connected w i t h a f r e e volume r e d u c t i o n . The r e v e r s i b l e a n e l a s t i c e f f e c t , too, seems t o be i n f l u - enced by t h e f r e e volume p r e s e n t i n t h e as-cast a l l o y s .

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ACKNOWLEDGMENTS

The research was c a r r i e d o u t w i t h CNR/GNSCl funds. The c o l l a b o r a t i o n o f fliss. 1. Zuc- c h i and Mr.

Pi.

Costa i s g r a t e f u l l y acknowledged.

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REFERENCES

/1/ B o n e t t i ,E., Evangel ista,E., Riontino,G., Al 1 i a ,P. and V i n a i ,F., J. Physique 44, C-9 (1983) 133.

/2/ Geer,A.R., J. Met. Sci., 17 (1982) 1117.

/3/ Allia,P. and V i n a i ,F., P h y c Rev. 826 (1982) 614. /4/ Gerling,R. and blagner,R., S c r i p t a

m.

17 (1983) 1129. /5/ Berry,B.S. and P r i tchet,ll.C., J.App1. P ~ S . 47 (1976) 3295. /6/ Guyot,F., Fouquet,F. and Perez,J. J. ~ h y s i q u ë 4 4 C-9 (1983) 139.

/7/ Chen,H.S., Sherwood,R.C., Jin,S. and Chi ,G.C., X A p p l . ~ h y s . 55 (1984) 1796. /8/ Hunger,G. and Mordike,B.L., Meta1 Science 16 (1982) 203.

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/9/ Freed,R.L. and Vander Sande,J.B., Met. T r a E . A, 10A (1979) 1621.

/ I O / Chi,G.C., Chen, H.S. and F,lillet, C.E., J.Appl, p h K 49 (1978) 1715.

/Il/ Allia,P., B o n e t t i ,E., Evangel ista,E., T u r r o n i

,

L. a n d T i n a i ,F., Phys. S t a t . Sol.(a)

-

88 (1985) 653.

TABLE 1

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R e l a t i v e average values f o r OF and EF f o r A and D t y p e specimens a t room temperature i n as-cast c o n d i t i o n s and a f t e r v a r i o u s ageing treatments

(O,, average values r e f e r r i n g t o D specimens a t room temperature).

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JOURNAL DE PHYSIQUE

io 10' 10' IO' 10% io 10' IO' ' 10 los

t (sec)

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Fig. 1

Md (a) and 9-1 ( b ) t r e n d s d u r i n g isothermal annealing a t 450 K o f as- -cast specimens o f t h e d i f f e r e n t s e r i e s (see t e x t ) .

Resonance frequency 3 x 1 0 ~ Hz. Mo,

'Qo

values a t t h e annealing temperature a t t h e s t a r t o f t h e anneal.

Fig. 2