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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 o p e r a t i n g at 25 kv in H. J. LE~MY and T. T. WANGare Members of the Technical Staff, Bell Telephone Laboratories, Inc., Murray Hill, N.J.H.S. CHEN, formerly Postdoctoral Associate, Yeshiva University,New York, N. Y., is now Staff Physicist, Allied Chemical Corp., Materials Research Center, Morristown, N. J. Manuscript submitted August 4, 1971. METALLURGICALTRANSACTIONS

the s e c o n d a r y e l e c t r o n e m i s s i o n mode. The compos i t i o n s , s t r u c t u r e s , and g l a s s t r a n s i t i o n and 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 s 2 of the a l l o y s e x a m i n e d in this i n v e s t i g a t i o n a r e s u m m a r i z e d in T a b l e I. The gold and copper alloying additions shown in Table I were s e l e c t e d b e c a u s e they i n c r e a s e the stability and g l a s s t r a n s i t i o n t e m p e r a t u r e of the b i n a r y alloy, p r e s u m a b l y by i n c r e a s i n g the c o n f i g u r a t i o n a l e n t r o p y and hence the s t a b i l i t y of the liquid phase. 2 T h i s effect is e v i denced by an i n c r e a s e in the 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 c , as shown in T a b l e I. The a m o r p h o u s - c r y s t a l l i n e t r a n s f o r m a t i o n in t h e s e alloys has been studied p r e v i o u s l y . F o r the b i n a r y a l loy, 2 c r y s t a l l i z a t i o n o c c u r s in t h r e e stages: a) h o m o geneous p r e c i p i t a t i o n of a v e r y f i n e - g r a i n e d , " m i c r o c r y s t a l l i n e " (20 to 100A) m e t a s t a b l e fcc phase within

Table I. Pd-Si Specimen Compositions, Heat Treatments, Structures, and Transformation Temperatures

No.

Composition, AtomicFractions HeatTreatment

Structure

Tg*

Tc*

362~

367~

372~

402~

373~

413~

1

Pdo.a2Sio.la

as quenched amorphous

2

Pd0.a2Sio.]s

350~ hr furnacecool

glass microcrystalline fcc + metastable

3

Pdo.s2Slo.ls

450~ hr furnacecool

fcc + metastable silicide

as quenched amorphous

sdicide

4

Pdo.79sAuo.o4Sio.16 s

5

Pdo.795Auo.o4Sio.16s 350~

6

Pdo.79sAuo.o4Sio.t6s

450~ hr. furnacecool

microcrystalline fcc + metastable sihclde

7

Pdo.7qs CUo.o6S10.16s

as quenched

amorphous

8

Pdo.77sCuo.o6 Sio.16s

350~

glass+ microcrystalhne fcc

hr.

hr

furnace cool

9

Pdo.7~sCuo.o6 Sio.]6s

450~ hr furnacecool

glass+ fcc mlcrocrystals

glass+ microcrystallinefcc + metastablesilicide

*Tg and Tc valuesfromRef. 2. Heatingrate = 20~ per rain.

VOLUME 3, MARCH 1972-699

|

o_o_ X

s

3

ca

L o. o2 , ~ u L ,

Z

gz

0)/~

O3 t~ f15

m ~ _1

N Z

+5*

o AL/L

Fig. 1--Load-elongation c u r v e s for the tensile s p e c i m e n s listed in Table I.

Table II. Mechanical Properties of PdSi Alloys

Num- DPH, ber kg/mm2 1 2 3

118 116 232

4 5 6

127 91 161

7 8 9

129 113 141

E, dyne/cm2

YS, dyne/era 2

UTS, dyne/cm2

TS

6.8 X 10n 8.25 X 1 0 9 2.7 • 101~ 0.0025 7.5X 10n 1.35Xl0 l~ 2.75X 10l~ 0.004 Specimensextremely 0 brittle no tensde data 8.5 X lOl* 9.5 X 109 2.7 X 10l~ 0.003 10X 10n