INTERNAL FRICTION ON SILICON BRONZE AT ELEVATED TEMPERATURES

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INTERNAL FRICTION ON SILICON BRONZE AT ELEVATED TEMPERATURES

S. Pilecki, J. Królikowski, R. Jemielniak

To cite this version:

S. Pilecki, J. Królikowski, R. Jemielniak. INTERNAL FRICTION ON SILICON BRONZE AT EL- EVATED TEMPERATURES. Journal de Physique Colloques, 1985, 46 (C10), pp.C10-395-C10-398.

�10.1051/jphyscol:19851089�. �jpa-00225474�

INTERNAL FRICTION ON SILICON BRONZE AT ELEVATED TEMPERATURES S. PILECKI, J. K R ~ L I K O W S K I and R. JEMIELNIAK

Institute of Fundamental Technological Research, polish Academy of Sciences, Swietokrzyska 21, 00-049 Warsaw, Poland

. .

Resume

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L ' e t u d e de f r i c t i o n i n t e r n e dans l e s e c h a n t i l l o n s de bronze au

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s i l i c i u m d ' u n e forme c i r c u l a i r e ( 4 30 mm) e t soumis aux v i b r a t i o n s t r a n s v e r s a l e s , a l ' a i d e de, l ' a p p a r e i l l a g e c o n s t r u i t dans c e b u t . La f r e q ~ e n c e des v i b r a t i o n s e t a i t env. q u i n z a i n e kHz e t l a t e m p e r a t u r e des e c h a n t i l l o n s v a r i a i t e n t r e 100 e t 800 K. Pour l e s e c h a n t i l l o n s soumis a l a d e f o r m a t i o n p l a s t i q u e ; on observe changements n o n - t y p i c a l de Q - ~ ( T ) : aux temperatures 400-500 K une d i m i n u i t i o n de f r i c t i o n i n t e r n e v e r s une

minimum. Les r e s u l t a t s obtenus p e r m e t t e n t d ' a v a n c e r l ' h y p o t h e s e que c e t t e d i m i n u t i o n de mobi l i t e des d i s l o c a t i o n s due a l a presence du compose Mn2Si.

A b s t r a c t

-

An i n t e r n a l f r i c t i o n s t u d y a t kHz frequency i n t h e t e m p e r a t u r e

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range 100-800 K was c a r r i e d o u t on a t e s t s t a n d o p e r a t i n g on t h e p r i n c i p l e o f f l e x u r a l v i b r a t i o n o f disk-shaped specimens ($ 30 mm) and measurement o f f r e e v i b r a t i n y decay r a t e . For c o l d-worked s i 1 i c o n bronze some a t y p i c a l changes on Q- ( T ) were found: i n t h e t e m e r a t u r e range 400-500 K t h e r e occurs an i n t e r n a l f r i c t i o n decrease t o a minimum value. T h i s means t h a t i n cold-worked s i l i c o n bronze t h e r e occurs some a t y p i c a l d i m i n u t i o n o f d i s l o c a t i o n m o b i l i t y , caused p r o b a b l y by MnpSi p a r t i c l e s .

The d e f e c t s c r e a t e d by c o l d - w o r k i n g i n f l u e n c e i n t e r n a l f r i c t i o n i n a r a t h e r t y p i c a l way: f o l l o w i n g a t e m p e r a t u r e i n c r e a s e , t h i s f r i c t i o n i n c r e a s e s as w e l l and v a r i o u s m a t e r i a l s i n some s p e c i f i c t e m p e r a t u r e and frequency range a r e

c h a r a c t e r i z e d w i t h inte.rna1 f r i c t i o n peaks. These peaks a r e caused by v a r i o u s d i s l o c a t i o n - d i s l o c a t i o n and d i s l o c a t i o n - p o i n t d e f e c t and/or atoms o f i m p u r i t i e s i n t e r a c t i o n s /1,2/.

I n t h e course o f i n v e s t i g a t i o n s o f cold-worked s i l i c o n bronze we have found t h a t t h e r e can o c c u r as w e l l a " n e g a t i v e peak," i .e., a d i m i n u t i o n o f i n t e r n a l f r i c t i o n w i t h i n t h e 400-500 K t e m p e r a t u r e range, and t h e n i t s repeated growth.

I 1

-

--- TEST STAND

A m a j o r i t y o f s t u d i e s o f i n t e r n a l f r i c t i o n c a r r i e d o u t i n t h e w o r l d uses m a i n l y an i n v e r t e d t o r s i o n pendulum w i t h a frequency o f about 1 Hz. However, o u r s t u d i e s were c a r r i e d o u t on a t e s t s t a n d o p e r a t i n g a c c o r d i n g t o a n o t h e r p r i n c i p l e ; a s h o r t d e s c r i p t i o n o f t h i s i s g i v e n below. A disk-shaped specimen o f 30 mm d i a m e t e r and 1-3 mm t h i c k n e s s i s s u p p o r t e d a t 3 p o i n t s , b e i n g t h e common nodes o f f l e x u r a l v i b r a t i o n o f two modes ( i n t e r s e c t i o n o f c i r c l e and t h r e e r a d i i d i s p l y e d by 120"). It i s l o c a t e d i n a vacuum vessel (vacuum o f t h e o r d e r o f 10- Pa). It

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19851089

C10-396 JOURNAL DE PHYSIQUE

c o u l d be heated up t o a temperature o f 900-1000 K and cooled by immersion t o g e t h e r w i t h t h e vacuum vessel i n l i q u i d n i t r o g e n o r ( i n f u t u r e ) i n l i q u i d helium. Thanks t o c o u p l i n g w i t h a minicomputer and p r i n t e r , a l l c o n t r o l l i n g , measuring and computing f u n c t i o n s w i t h i n complete working range a r e f u l l y automated. The stand enables determinations o f Poisson's r a t i o , Young's modulus and i n t e r n a l f r i c t i o n . It operates on t h e p r i n c i p l e o f e x c i t a t i o n and measurement o f resonance

frequencies o f f l e x u r a l v i b r a t i o n o f two modes, f o and f3. I n t r o d u c i n g

frequencies fo and f3, t h e i r modes, dimensions o f specimen and d e n s i t y o f m a t e r i a l i n t o equations o f v i b r a t i o n o f c i r c u l a r p l a t e s one can f i n d P o i s s o n ' s r a t i o and Young's modulus /3/. I n t u r n , from measurements o f t h e amplitude o f f r e e

v i b r a t i o n , decaying a f t e r s w i t c h i n g o f t h e e x c i t a t i o n o f resonance v i b r a t i o n , one

f

can determine t h e i n t e r n a l f r i c t i o n Q-

.

The r e s u l t s o f those measurements and computations i n t h e form o f numbers and d o t diagrams a r e recorded on a p r i n t e r . S p e c i f i c f e a t u r e s o f t h e stand a r e as f o l l o w s : p o s s i b i l i t y o f i n v e s t i g a t i o n o f any s o l i d s ( n o n - m e t a l l i c specimens must be s u r f a c e m e t a l l i z e d , e.g. by means o f vacuum d e p o s i t i o n ) ; temperature range 100-1000 K ( i n f u t u r e 4.2

-

1000 K);

accuracy o f temperature measurement 0.1 deg; minimum temperature s t e p 1-2 deg;

vacuum o f chamber Pa; resonance frequencies o f 1-3 mm thickness, fo = 8-20 kHz, f3 = 10-26 kHz; accuracy o f frequency measurement 1 Hz; automatic adjustment o f t h e d i s t a n c e " e x c i t i n g electrode-specimen," locked d u r i n g measurement o f resonance frequencies and i n t e r n a l f r i c t i o n ; f u l l automation o f measuring- m o n i t o r i n g process ( h e a t i n g speed, temperature step, measurement o f resonance frequencies, c o u n t i n g o f p e r i o d s and measurement o f amplitude o f f r e e v i b r a t i o n , computations, p r i n t o u t and drawing o f r e s u l t s o f P o i s s o n ' s r a t i o , Young's modulus and i n t e r n a l f r i c t i o n versus temperature).

The most important advantages o f t h e method are: s i m p l i c i t y o f change o f specimen temperature up t o ca. 1000 K; small amplitude o f deformation (e.g. a t frequency 20 kHz i t i s o f t h e o r d e r o f m)

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i n t h i s connection p r a c t i c a l l y o n l y t h e l i n e a r r e g i o n i s u t i l i z i e d and second o r d e r e f f e c t s do not occur; c o u p l i n g o f specimen w i t h e x c i t i n g - r e c e i v i ng electode i s weak and t h e r e f o r e i t s i n f l u e n c e i s n e g l i g i b l e when compared w i t h i n t e r n a l losses i n specimen. For those reasons t h i s method i s e s p e c i a l l y s u i t b l e f o r s t u d y i n g t h e specimens o f h i g h q u a l i t y f a c t o r Q, even o f

t

t h e order of 10

-lo6;

wide range o f working frequencies, depending on t h e t h i c k n e s s o f specimens.

On t h i s t e s t stand

-

i n p a r a l l e l t o i t s improvement

-

i n 1982-1984 a number o f s t u d i e s were performed, among o t h e r s t h e i n f l u e n c e o f mechanical s t r a i n and a c t i o n o f h y d r o s t a t i c pressure on Q - ~ ( T ) i n commercial grade copper, brass and aluminium were t e s t e d . It was found, e.g., t h a t changes r e s u l t i n g from t h e a c t i o n o f h y d r o s t a t i c pressure a r e s i m i l a r t o changes caused by cold-working operations.

I 1 1

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MATERIALS

For examinations described i n t h i s paper t h e f o l l o w i n g t e c h n i c a l a l l o y s were used:

1) MO-58 brass (composition: Cu 56-60%, Zn ca.40%, Pb 1-3.5%, o t h e r s 0.7%);

2) BK-31 bronze (composition: Cu 94-952, Si 2.7-3.5%, Mn 1-1.5%, o t h e r s 1.1%);

3) BK-1044 bronze (composition: Ni 3.5-5.5%, A1 9.5-11%, Fe 3.5-5.58, Cu-rest).

EXPERIMENTAL PROCEDURE 1"

-

m)-58 and BK-1044 a l l o y s were t e s t e d i n two s t a t e s :

1) specimens c u t o u t from t h e r o d were heated d u r i n g measurement up t o t h e temperature a t which t h e r e was s t i l l measurable i n t e r n a l f r i c t i o n ( t i m e o f measurement from minimum up t o maximum temperature: 4-8 hours, t i m e o f h o l d i n g a t a temperature c l o s e t o t h e maximum one: ca. 1 h ) ;

2) a f t e r c o o l i n g o f t h e specimen t o g e t h e r w i t h t h e stand

-

w i t h o u t t a k i n g o u t

-

repeated h e a t i n g and measurement.

A BK-31 a l l o y was t e s t e d i n t h e above described manner. A d d i t i o n a l l y two rods were compressed a x i a l l y by ca. 4.5% and ca. 15% and specimens c u t o u t from those rods were t e s t e d i n t h e same way.

d i f f e r e d s l i g h t l y , p r o b a b l y beacuse o f some i n h e r e n t d i f f e r e n c e s i n t h e i r dimensions. On t h e f i g u r e s a r e shown averaged r e s u l t s f r o m 3 specimens. The f i r s t measurements were c a r r i e d o u t w i t h i n t h e whole a v a i l a b l e t e m p e r a t u r e range, i .e., s t a r t i n g from ca. 100 K. As i t was found t h a t i n t e r e s t i n g e f f e c t s o c c u r above 400 K, f u r t h e r measurements were performed s t a r t i n g f r o m room temperature.

The a t t a i n a b l e maximum t e m p e r a t u r e depended on t h e v a l u e o f t h e a m p l i t u d e o f specimen v i b r a t i o n ; when t h i s a m p l i t u d e was t o o l o w t o be measured, t h e n f u r t h e r i n c r e a s e s of temperature were useless.

V

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E_X_P_ERIMENTAL RESULTS

I n MO-58 brass a t y p i c a l dependence o f t h e measured q u a n t i t i e s on t e m p e r a t u r e was found: w i t h an i n c r e a s e o f temp r a t u r e t h e e l a s t i c c o n s t a n t s e x h i b i t an almost

f

l i n e a r change (Fig. I ) , w h i l e Q- ( T ) i n i t i a l l y r i s e s i n a v e r y g e n t l e manner and ab ve 450 K t h i s r i s e i s v e r y f a s t ( F i g . 2).

P

I n cold-worked m a t e r i a l t h e v a l u e o f Q- ( T ) i n a l l temperature ranges i s n o t a p p a r e n t l y d i f f e r e n t from i t s v a l u e i n annealed m a t e r i a l . D i f f e r e n c e s o f t h o s e values appearing between 3 specimens used f o r t e s t s and caused by t o l e r a n c e s of specimen dimensions were g r e a t e r t h a n d i f f e r e n c e s o c c u r r i n g i n t h e same specimen i n t h e cold-worked and annealed s t a t e . These f a c t s i n d i c a t e t h a t w i t h i n a l l t h e used t e m p e r a t u r e range (100-600 K) c o l d - w o r k i n g and f u r t h e r a n n e a l i n g , caused by h e a t i n g of m a t e r i a l d u r i n g a f i r s t t e s t do n o t have an e v i d e n t i n f l u e n c e on t h e p o s s ' i b i l i t y o f displacement o f d i s l o c a t i o n loops. Such displacements o f d i s l o c a t i o n loops should be r e s p o n s i b l e f o r i n t e r n a l f r i c t i o n a t low a m p l i t u d e o f deformation /4/.

I n cold-worked BK-31 s i l i c o n bronze ( c u t f r o m r o d ) e l a s t i c c o n s t a n t s a r e s u b j e c t e d t o r a t h e r t y p i c a l changes, w h i l e i t i s n o t so w i t h i n t e r n a l f r i c t i o n . I n t h e cold-worked bronze an unusual and i n t e r e s t i n g e f f e c t was observed ( F i g . 3 ) ; a f t e r g e n t l e and t y p i c a l growth of i n t e r n a l f r i c t i o n i n t h e 100-400 K t e m p e r a t u r e range, above ca. 400 K a drop o f i n t e r n a l f r i c t i o n s t a r t 1 t h a t l a s t s up t o ca. 520 K and t h e n t y p i c a l growth f o l l o w s . A f t e r annealing, Q- ( T ) a t low temperature i s c o n s i d e r a b l y l o w e r t h a i n t h e cold-worked s t a t e , a t a t e m p e r a t u r e about 200 K e v i d e n t i n c r e a s e i n Q-' occurs, resembling p a r t o f t h e peaks d e s c r i b e d i n /I/ and found i n c o n c e n t r a t e d copper a l l o y s , w h i l e above 500 K i t i s p r a c t i c a l l y t h e same as i n t h e cold-worked s t a t e .

Fig. 1. P o i s s o n ' s r a t i o and Young's Fig. 2. I n t e r n a l f r i c t i o n o f MO-58 brass.

modulus o f MO-58 brass.

V) '7

10-~f M0-58 brass

I n an a d d i t i o n a l l y cold-worked (compressed by ca. 4.5% and ca. 15%) BK-31 bronze, t h e i n t e r n a l f r i c t i o n i s s u b j e c t e d t o s i m i l a r changes (Figs. 4 and 5). The degree o f cold-work r e s u l t s i n some q u a n t i t a t i v e changes o n l y , w h i l e t h e " n e g a t i v e peak"

p e r s i s t s i n a s t a b l e manner.

.- 0

5 5::

.-

.

.36 ^{+ ..}

5 2.

E

0.. cold-worked

x r x annealed

.

L X

.35

-

^{E I o-($} _{; Z X} ^{0 %}

^#

5::

.34

2..

.

^*:;x=

: : x x

200 400 603

Temperature [ K ] 200 400 600

Temperoture [K]

C10-398 JOURNAL DE PHYSIQUE

I n BK-1044 bronze t h e changes i n i n t e r n a l f r i c t i o n were found t o be q u a l i t a t i v e l y c l o s e t o t h o s o c c u r r i n g i n BK-31 bronze, b u t s m a l l e r ( F i g . 6). With r e s p e c t t o changes i n Q- ( T ) , t h e BK-1044 bronze h o l d s an i n t e r m e d i a t e p o s i t i o n t h e r e f o r e

f

between BK-31 bronze and MO-58 brass.

BK-31 bronze I cold-wwked 1457.k

******, x r x annealed

l

3 0 0 U X ) 5 0 0 6 a ) 7 6 0 Temperature [ K ] Fig. 3. I n t e r n a l f r i c t i o n o f BK-31 bronze as c u t o u t from t h e rod.

BK-3 bronze

cold worked (15%)

;

x x x annealed

B K - ~ I bronze

*** cold-worked

x x x annealed

*

X

MO

400 600 Ternperatre [ K l Fig. 4. I n t e r n a l f r i c t i o n o f BK-31 bronze a d d i t i o n a l l y deformed by 4.5%.

BK-I044 bronze

**.

Cold-worked

x x x annealed

*"xX

**..

. .

^0..

*.*... ^{tix .*}

^{x X}

x X X X x X x X x X x x x x ~ X

I : L .

300 400 500 600 700 300 400 500

600

700

Tempemture [ K1 Tempemture [ K ]

Fig. 5. I n t e r n a l f r i c t i o n o f BK-31 Fig. 6. I n t e r n a l f r i c t i o n o f BK-1044 bronze a d d i t o n a l l y deformed by 15%. bronze as c u t o u t from t h e rod.

V I

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DISCUSSION

Taking i n t o account t h a t i n t e r n a l f r i c t i o n and i t s peaks a r e caused and shaped by m o t i o n o f d i s l o c a t i o n l o o p s pinned and depinned by p o i n t d e f e c t s and s o l u t e atoms, one s h o u l d assume t h a t " n e g a t i v e peaks" i n s i l i c o n bronze s h o u l d be caused by an a d d i t i o n a l p i n n i n g process. An i n v e s t i g a t i o n o f t h i s process and d e t e r m i n a t i o n of t h e t y p e o f d e f e c t s o f atoms r e s p o n s i b l e f o r t h i s phenomenon i s a c u r r e n t t a s k f o r t h e authors. Probably, i t may be caused by Mn2Si p a r t i c l e s which i n t h e s i l i c o n bronze can occur a t e l e v a t e d temperature. The f a c t t h a t i n BK-1044 bronze of chemical composition d i f f e r e n t from BK-31 bronze t h i s e f f e c t occurs on a s m a l l e r scale, though a l l o y a d d i t i o n s f o r b o t h bronzes a r e d i f f e r e n t , i s a p r o o f of t h e c o m p l e x i t y o f t h e problem.

REFERENCES

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/1/ Kong, Q. O., Lucke, K. and Sokolowski, G., Proc. 7 t h ICIFUAS, J. de Physique 42 (1981) C5

-

271.

/2/ Schmidt, H., Lenz, D., Drescher, E. and Lucke, K. i b i d , C5

-

339.

/3/ NartinEek G., J. Sound Vibr. 2 (1965) 116.

/4/ Granato, A. V. and Lucke, K.,

7.

Appl. Phys.

27

(1956) 583.