MECHANICAL PROPERTIES OF (Fe, Co, Ni)-M-B (M=Ti, Zr, Hf, V, Nb, Ta AND Mo) AMORPHOUS ALLOYS WITH LOW BORON CONCENTRATION

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MECHANICAL PROPERTIES OF (Fe, Co, Ni)-M-B

(M=Ti, Zr, Hf, V, Nb, Ta AND Mo) AMORPHOUS

ALLOYS WITH LOW BORON CONCENTRATION

a . Inoue, K. Kobayashi, M. Nose, T. Masumoto

To cite this version:

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JOURNAL DE PHYSIQUE

CoZZoque C8, suppl6rnent au n08, Tome

41,

aoct 1980, page

C8-831

MECHANICAL PROPERTIES OF ( ~

,

e C o , ~ i ) - M - G

( M = T ~ ,

Zr,

H f ,

V,

Nb,Ta

AND

MO)

AMORPHOUS ALLOYS

WITH

LOW BORON CONCENTPATION

*X

A. I n o u e , K. ~ o b a ~ a s h i * , M. Nose and T. Masumoto

,

The research I n s k i t u t s for rron, S t e e l and Other Metals, Tohoku U n i v e r s i t y , Sendai 980, Japan.

..

Japan Metals

and Cherrticals Co. Ltd., Ohmama-cho

376-01,

G u m , Japan.

Swnitomo Special Mztals Co. Ltd., Chsaka

564,

Japan.

INTRODUCTION I d e n t i f i c a t i o n of t h e as-quenched p h a s e s was made by To d a t e a l a r g e number of amorphous a l l o y s have

been produced by t h e m e l t quenching t e c h n i q u e . Broadly s p e a k i n g , t h e s e a l l o y s c a n b e c l a s s i f i e d i n t o two c a t e g o r i e s . One i s t h e m e t a l - m e t a l l o i d t y p e c o n s i s t i n g of a t r a n s i t i o n m e t a l and a m e t a l - l o i d e l e m e n t s u c h a s P, S i , C o r B. The o t h e r is t h e e a r l y t r a n s i t i o n m e t a l ( e . g . , T i , Zr e t c . ) a l l o y - ed w i t h a l a t e t r a n s i t i o n m e t a l ( e . g . , Co, N i , Cu e t c . ) . Most amorphous a l l o y s b e l o n g t o t h e f o r m e r t y p e and t h e y a l w a y s c o n t a i n a b o u t 15-30 a t . % m e t a l - l o i d e l e m e n t s . On t h e o t h e r hand, t h e amorphous a l - l o y s b e l o n g i n g t o t h e l a t t e r t y p e u s u a l l y c o n t a i n s o l u t e m e t a l s more t h a n a b o u t 30 a t . % a s e x e m p l i f i e d f o r Cu-Ti, Cu-Zr and Ni-Nb.

R e c e n t l y , we h a v e found t h a t a n amorphous s i n - g l e p h a s e i s formed i n a wide c o m p o s i t i o n r a n g e of (Fe, Co, Hi)-IV o r V g r o u p t r a n s i t i o n metal-B t e r n a - r y a l l o y s c o n t a i n i n g l e s s t h a n 1 0 a t . % B . F u r t h e r ,

t h e s e amorphous a l l o y s c o n t a i n l e s s t h a n a b o u t 20 a t . % of t h e IV o r V g r o u p t r a n s i t i o n m e t a l s and t h u s a r e i n t e r e s t i n g m a t e r i a l s from i n d u s t r i a l p o i n t of view b e c a u s e of h i g h c o n c e n t r a t i o n of f e r r o m a g n e t i c

e l e m e n t s s u c h a s F e , Co and N i . The aim of t h i s p a p e r i s t o p r e s e n t t h e c o m p o s i t i o n r a n g e o f Fe, Co o r Ni-IV o r V group t r a n s i t i o n metal-B t e r n a r y amorphous p h a s e and t h e c o m p o s i t i o n dependence of m e -

c h a n i c a l p r o p e r t i e s of t h e s e amorphous a l l o y s .

EXPERIMENTAL

A l l o y s used i n t h e p r e s e n t wprk q r e of , t h e Fe, Co o r N i - I V o r V g r o u p t r a n s i t i o n metal-B t e r n a r y s y s t e m s s u c h a s (Fe, Co, N i ) - ( T i , Z r , Hf, V. Nb, Ta, Mo)-B. M i x t u r e s of p u r e m e t a l s and boron were m e l t - ed i n a r g o n a t m o s p h e r e i n a n a r c - o r a n i n d u c t i o n f u r n a c e . Continuous r i b b o n specimens o f 1 mm w i d t h and 0.02 mm t h i c k n e s s were p r e p a r e d by m e l t s p i n - n i n g . T y p i c a l l y , t h e amount of a l l o y s m e l t e d i n one r u n was a b o u t 2 g and t h e r o t a t i o n s p e e d of t h e s t e e l r o l l e r ( 2 0 cm i n d i a m e t e r ) was a b o u t 6000 rpm.

c o n v e n t i o n a l X-ray d i f f r a c t i o n and t r a n s m i s s i o n e- l e c t r o n microscopy t e c h n i q u e s . Hardness was meas- u r e d by a V i c k e r s m i c r o h a r d n e s s t e s t e r w i t h a 100 g l o a d . Each h a r d n e s s v a l u e was t h e a v e r a g e o f s e v e n t o t e n i n d e n t a t i o n s . 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 was examined by a d i f f e r e n t i a l t h e r m a l analyzer(DTA1 a t a h e a t i n g r a t e o f 8 . 3 3 x K / s . D u c t i l i t y was e v a l u a t e d by m e a s u r i n g t h e r a d i u s of c u r v a t u r e a t f r a c t u r e i n a s i m p l e bend t e s t / I / . The deformed s t r u c t u r e and t h e f r a c t u r e s u r f a c e w e r e o b s e r v e d by a s c a n n i n g e l e c t r o n m i c r o s c o p e .

RESULTS

1. Formation r a n g e of t h e amorphous p h a s e

The c o m p l e t e l y amorphous p h a s e i s o b t a i n e d i n wide c o m p o s i t i o n r a n g e s o f Co-Ti-B, Fe-Zr-B, Co-Zr- B, Ni-Zr-B, Fe-Hf-B, Co-Hf-B, Ni-Hf-B, Fe-Nb-B, CO- Nb-B, Co-Ta-B, Ni-Ta-B and Co-Mo-B s y s t e m s . A s ex- amples, F i g . 1 shows t h e f o r m a t i o n r a n g e s o f qhe

I amorphous p h a s e i n Fe-Nb-B, Co-Nb-B, Co-Ta-B and Ni-Ta-B s y s t e m s i n which t h r e e e l e m e n t s a r e e s s e n - t i a l f o r t h e f o r m a t i o n of amorphous p h a s e . On t h e o t h e r hand, t h e f o r m a t i o n r a n g e s of t h e o t h e r amorphous a l l o y s a r e o m i t t e d b e c a u s e amorphous s i n g l e p h a s e h a s b e e n formed i n Co-Ti / 2 / , (Fe, Co, Ni)-Zr /3,4/ and ( F e , Co, Ni)-Hf / 5 , 6 / b i n a r y s y s t e m s and t h e a d d i t i o n of B i s n o t always n e c e s s a r y f o r t h e f o r m a t i o n of amorphous p h a s e . As s e e n i n t h e f i g - u r e , t h e s e amorphous a l l o y s a r e l i m i t e d t o t h e r a n g e more t h a n a b o u t 2 a t . % B and t h e a l l o y i n g

ele-

ments a r e l i m i t e d t o t h e r a n g e s of 10-14 at.%Nb f o r Fe-Nb-B, 7-22 at.%Nb f o r Co-Nb-B, 8-20 a t . % T a f o r Co-Ta-B and 10-23 at.%Ta f o r Ni-Ta-B. The forma-

t i o n r a n g e becomes n a r r o w e r i n t h e o r d e r of t h e Co- Zr-B > Co-Hf-B > Co-Ti-B > Co-Nb-B > Co-Ta-B > Fe- Zr-B > Fe-Hf-B > Ni-Zr-B > Ni-Hf-B > Ni-Ta-B > Fe- Nb-B s y s t e m s and no amorphous p h a s e was found i n

t h e a l l o y s y s t e m s o f (Fe, Ni)-Ti-B, ( F e , Co, Nil-V- B. Ni-Nb-B and Fe-Ta-B.

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JOURNAL DE PHYSIQUE

Crystalline

C

Amorphous

6

0 2

4

6

8

10

Boron

(

at0l0)

F i g . 1 Composition r a n g e s f o r t h e f o r m a t i o n of amorphous s i n g l e phase i n t h e Fe-Nb-B, Co- Nb-B, Co-Ta-B and Ni-Ta-B s y s t e m s .

Melt-quenched e u t e c t i c (Fe, Co)-Nb and (Co, Ni) -Ta b i n a r y a l l o y s show a c r y s t a l l i n e s t r u c t u r e w i t h - o u t a n y t r a c e of amorphous phase. On t h e o t h e r hand, t h e a l l o y s w i t h a s 1 o w ' a s . a b o u t 2 a t . % B show a n amorphous s t r u c t u r e . From t h e s e f a c t s , i t i s concluded t h a t t h e s i m u l t a n e o u s d i s s o l u t i o n of Nb o r Ta and B enhances t h e amorphous-forming tendency of t h e i r a l l o y s . T h a t i s , i t i s assumed t h a t t h e bond- i n g f o r c e between m e t a l and m e t a l a s w e l l a s m e t a l and m e t a l l o i d p l a y s a n i m p o r t a n t r o l e i n t h e forma- t i o n o f a n amorphous p h a s e i n t h e a l l o y s i n v e s t i - g a t e d i n t h e p r e s e n t work. T h i s a s s u m p t i o n a l s o r e c e i v e s s u p p o r t from t h e f a c t t h a t m e t a l - m e t a l t y p e amorphous p h a s e i s formed i n t h e b i n a r y a l l o y sys- tems c o n s i s t i n g of Fe, Co o r N i and T i , Zr o r ' H f which a r e c o n s i d e r e d t o p o s s e s s s t r o n g e r bonding f o r c e compared w i t h t h a t between Fe, Co o r N i and Nb o r Ta.

2. Mechanical p r o p e r t i e s

The V i c k e r s h a r d n e s s v a l u e s ( H v ) of (Fe, Co, Ni) 94-xMxB6(M=Ti, Z r , Hf, Nb and Ta) t e r n a r y amorphous a l l o y s a r e p l o t t e d a s a f u n c t i o n o f t h e c o n c e n t r a - t i o n of a l l o y i n g e l e m e n t s M i n F i g . 2 . A s s e e n i n t h e f i g u r e ( a ) , ( b ) and ( c ) , t h e h a r d n e s s v a l u e s i n c r e a s e s i g n i f i c a n t l y w i t h i n c r e a s i n g amount of a l l o y i n g e l e m e n t s , i n d i c a t i n g t h a t t h e bonding f o r c e between a l l o y i n g e l e m e n t M and B i s much s t r o n g e r t h a n t h a t between F e , Co o r N i and B. F u r t h e r , one c a n n o t i c e t h a t t h e h a r d n e s s v a l u e i s h i g h e s t f o r

I 4

io

b

i;

1; 1;

io

i 2

M

(at '10 )

F i g . 2 Change i n V i c k e r s h a r d n e s s ( H v ) f o r Fe9,i-xMx B6, C O ~ ~ - ~ M , B ~ and N ~ C J ~ - ~ M , B ~ ( M = T ~ , Z r , Hf, Nb and Ta) amorphous a l l o y s w i t h t h e amount of a l l o y i n g e l e m e n t s M.

t h e a l l o y s c o n t a i n i n g Hf and d e c r e a s e s i n t h e o r d e r of Zr > Ta > T i > Nb. T h i s tendency i s t h e same i n t h e t h r e e a l l o y s y s t e m s o f Fe, Co and N i , i n d i c a t - i n g t h a t t h e bonding f o r c e between M and Fe, Co o r N i o r M and B d e c r e a s e s i n t h e o r d e r o f Hf > Zr >

Ta > T i > Nb. The h i g h e s t h a r d n e s s v a l u e o b t a i n e d

i s a b o u t 1000 DPN f o r CogoHfl4B6 a l l o y .

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t h e B c o n c e n t r a t i o n . The h a r d n e s s v a l u e i n c r e a s e s w i t h i n c r e a s i n g B c o n t e n t and t h e i n c r e a s i n g r a t e i s l a r g e s t f o r t h e Co-base a l l o y s . F u r t h e r , s i m i l a r t o t h a t f o r ( F e , Co, Ni)g4-xMxB6 a l l o y s , t h e h a r d n e s s v a l u e d e c r e a s e s i n t h e o r d e r of Hf > Zr > Ta > Nb s y s t e m s . The h i g h e s t h a r d n e s s v a l u e i n t h e s e a l l o y s y s t e m s i s a b o u t 1000 DPN f o r CogoHfl2Bg a l l o y s . 5 0 0 ~ 2 L 6 B 0 2 L 6 B 0 2 L 6 8

Boron (at%) Boron (at%) Baon ( a t % ) F i g . 3 Change i n V i c k e r s h a r d n e s s ( H v ) f o r Fegg-,

M12Bx, and Ni88-xM12~x(M=Ti, Z r ,

Hf, Nb and Ta) amorphous a l l o y s w i t h B con- t e n t .

A l l t h e amorphous a l l o y s of t h e p r e s e n t s y s t e m s p o s s e s s good bend d u c t i l i t y , a s i n t h e c a s e o f t y p i - c a l m e t a l - m e t a l l o i d o r m e t a l - m e t a l amorphous a l l o y s . D u c t i l e - b r i t t l e t r a n s i t i o n b e h a v i o r o f Feg2M12B6, Cog2M12Bg and Nis2M12B6(M=Ti, Zr, Hf, Nb and Ta) T a b l e I 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 ( T x ) , c r i t i c a l

f r a c t u r e t e m p e r a t u r e ( T f ) , Tf/T, and V i c k e r s h a r d n e s s ( H v ) f o r Fe82(Zr, Hf, Nb)12B6, Cog2 ( T i , Z r , Hf, Nb, Ta)12B6 and Ni82(Zr, Hf, Ta)12Bg t e r n a r y amorphous a l l o y s .

3

ITx : (Co,Ni)-(Nb.Ta)

>

Ni-(Zr

.Hf)

>

Co-(Ti,Zr,M),%Nb

>

Fe-( 2r.M )

Tx.Hv: Fe-(2r.M)

>

Co-(Ti.Zr,Hf ).Fe-Nb

>

Ni-(Zr.Ht

>

(Co.Ni)-(M.Ta)

amorphous a l l o y s was examined a s a f u n c t i o n o f a g i n g t e m p e r a t u r e f o r 3600 s and t h e d a t a a r e shown i n T a b l e I t o g e t h e r w i t h t h e c r y s t a l l i z a t i o n tempera- t u r e ( T x ) , Tf/Tx and h a r d n e s s . Tx i s t h e t e m p e r a t u r e d e t e r m i n e d a s b e i n g t h e b e g i n n i n g p o i n t of t h e f i r s t e x o t h e r m i c peak o n t h e DTA c u r v e s . As summarized b e n e a t h t h e t a b l e , Tf/Tx d e c r e a s e s i n t h e o r d e r of

(Co, Ni)-(Nb, Ta) > Ni-(Zr, H f ) > Co-(Ti, Z r , H f ) , Fe-Nb > Fe-(Zr, H f ) , i n c o n t r a s t t o t h e o r d e r o f h a r d n e s s . T h a t i s , t h e e m b r i t t l e m e n t t e n d e n c y i n - c r e a s e s w i t h i n c r e a s i n g bonding f o r c e among t h e con- s t i t u e n t e l e m e n t s i n t h e a l l o y s . Alloy System ( at "1. ) FeazZrtzBs Fe~zttflzBs Fes~NbrSo CorzTtnBs CoezZrqaBe COazHflzb C0azN4aBs ComTalaBe NimZrtzBe NiaMlaBs Nis2TaqzBs DISCUSSION ' Critical Frac- ture Temp Tf (K,x3.6ks) 5 6 3 5 9 8 6 2 3 6 1 3 6 4 8 6 9 8 7 4 3 7 5 3 6 8 3 6 9 3 6 9 3 Crystdliza- tion Temp Tx ( K ) 8 6 8 8 8 5 8 2 0 8 3 3 7 8 2 8 2 0 7 0 5 7 2 3 7 0 3 7 2 5 6 5 3 The e f f e c t o f a l l o y a d d i t i o n on t h e Tx and H, of amorphous a l l o y s h a s b e e n examined by some i n v e s - t i g a t o r s 17-11/ f o r t h e t r a n s i t i o n m e t a l s ( T i , V , C r , Mo, W , Mn, Fe, Co, N i , Cu) b e l o n g i n g t o t h e f o u r t h p e r i o d o r t h e V I g r o u p i n t h e p e r i o d i c t a b l e . How- e v e r , t h e r e i s h a r d l y any s y s t e m a t i c i n f o r m a t i o n o n s u c h a n e f f e c t f o r amorphous a l l o y s c o n t a i n i n g t h e I V and V g r o u p m e t a l s ( T i , Z r , Hf, Nb, Ta) w i t h h i g h r e a c t i v i t y and h i g h m e l t i n g p o i n t . The p r e s e n t i n - v e s t i g a t i o n s p r o v i d e some i n s i g h t i n t o t h e r o l e o f t h e s e r e f r a c t o r y m e t a l s on t h e s t r e n g t h of amorphous a l l o y s .

The h a r d n e s s v a l u e s of (Fe, Co, Ni)82M12B6(M= T i , Z r , H f , Nb and Ta) t e r n a r y amorphous a l l o y s a r e p l o t t e d a g a i n s t t h e g r o u p number of a l l o y i n g e l e - ments M i n F i g . 4. As shown i n t h e p r e v i o u s s e c - t i o n , t h e h a r d n e s s v a l u e d e c r e a s e s i n t h e o r d e r o f T

Kx

0 . 6 4 0 . 6 8 0 . 7 6 0 . 7 4 0.83 0 . 8 5 1 . 0 5 1 . 0 4 0.97 0 . 9 6

1 . 0 6 _{F i g .}₄ _{Change i n V i c k e r s hardness(H,)} _{f o r Fe82M12}

Bg, Cog2Ml2Bg and Ni82M12Bg(M=Ti, Z r , H f ,

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JOURNAL DE PHYSIQUE

Hf > Zr > Ta > T i > Nb f o r t h e Fe-, Co- and Ni-base a l l o y s , i n d i c a t i n g t h e tendency t h a t t h e h a r d n e s s o f

t h e amorphous a l l o y s i n c r e a s e s w i t h i n c r e a s i n g d i f - f e r e n c e o f t h e g r o u p number a n d / o r t h e p e r i o d i c num- b e r between t h e b a s e m e t a l ( F e , Co o r Ni) and t h e a l - l o y i n g e l e m e n t . We t r i e d t o e x p l a i n t h e r e a s o n f o r s u c h a tendency by v a r i o u s f a c t o r s s u c h a s a v e r a g e o u t e r e l e c t r o n c o n c e n t r a t i o n , a t o m i c s i z e , e l e c t r o - n e g a t i v i t y and t h e h a r d n e s s and m e l t i n g p o i n t of i n t e r m e t a l l i c compounds i n ( F e , Co, Ni)-M b i n a r y a l - l o y s which have been c o n s i d e r e d t o b e i m p o r t a n t f o r u n d e r s t a n d i n g t h e e f f e c t of a l l o y i n g e l e m e n t s 17-

111.

A s a r e s u l t , we have found f o r ( F e , Co, N i ) g 2 M12B6 t e r n a r y amorphous a l l o y s t h a t t h e r e e x i s t s a n a p p a r e n t l i n e a r r e l z t i o n s h i p between t h e h a r d n e s s

I I

Difference of ELectronegativity between

Fe,CoorNi and M(Zr.M,Nb.Ta)(after Pauling)

F i g . 5 R e l a t i o n between V i c k e r s h a r d n e s s ( H v ) and t h e d i f f e r e n c e i n e l e c t r o n e g a t i v i t y between Fe, Co o r N i and M(Zr, Hf, Nb, Ta) f o r Feg2 M12B6, Cog2M12B6 and Ni82M12B6 amorphous a l l o y s .

r

1 5 1

1

I 1 I I I

0.3

04

0.5

0.6

0.7

0.8

Difference

of

Electronegativity between

B

and M ( Z r

.

Hf

,

Nb .Ta )(after

Paulingl

F i g . 6 R e l a t i o n between V i c k e r s h a r d n e s s ( H v ) and t h e d i f f e r e n c e i n e l e c t r o n e g a t i v i t y between B and M(Zr, Hf, Nb, Ta) f o r Feg2M12B6, Cog2 M12Bg and Ni82M12B6 amorphous a l l o y s .

v a l u e s and t h e d i f f e r e n c e o f e l e c t r o n e g a t i v i t y b e t - ween t h e b a s e m e t a l ( F e , C o , Ni) and M o r t h e m e t a l - l o i d ( B ) and M . The r e s u l t i s shown i n F i g s . 5 and 6 and o n e c a n n o t i c e t h a t t h e l a r g e r t h e d i f f e r e n c e i n e l e c t r o n e g a t i v i t y , t h e h i g h e r i s t h e h a r d n e s s . Such a n a p p a r e n t l i n e a r r e l a t i o n s h i p was n o t e s t a b l i s h e d between t h e h a r d n e s s v a l u e s and t h e o t h e r f a c t o r s . J u d g i n g from t h e f a c t t h a t t h e h a r d n e s s v a l u e s a r e s i g n i f i c a n t l y i n f l u e n c e d by t h e d i f f e r e n c e of t h e e l e c t r o n e g a t i v i t y among t h e c o n s t i t u e n t e l e m e n t s , i t i s c o n c l u d e d t h a t a s t r o n g c h e m i c a l b o n d i n g between t h e b a s e m e t a l ( F e , Co, Ni) and M(Ti, Z r , Hf, Nb, Ta) o r B and M p l a y s a n i m p o r t a n t r o l e i n t h e h a r d n e s s of t h e amorphous a l l o y s f o u n d i n t h e p r e s e n t work.

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