Hydrogen solubility as a probe for monitoring recovery in palladium

Scripta

METALLURGICA

HYDROGEN

Vol, 9, pp, 1 0 6 3 - 1 0 6 8 , 1975 P r i n t e d in the U n i t e d S t a t e s

SOLUBILITY Ted

B.

AS A P R O B E

FOR

F l a n a g a n , J. F. Department

MONITORING

Pergamon

RECOVERY

L y n c h and J. of C h e m i s t r y

D.

Press~

IN P A L L A D I U M

Clewley

and B. von T u r k o v i c h Mechanical Engineering Department U n i v e r s i t y of V e r m o n t Burlington, Vermont (Received

Considering of r e c o v e r y ient

for the

Electrical and

some

large

(2)

during

as e l e c t r o n

monitoring

cusses

the

use

course

of r e c o v e r y

(4),

have

was

locations

and

have

extensively

atoms

gaseous

species

be

One

established

interest been

does

tained

K (6) at

not

and

even

studies

low and

until

there

bulk

high

palladium

is no r e a s o n

temperatures.

why

field

for the dis-

the

in the

friction

been

alloy

Evidence segre-

the

dis-

measurements of s o l u t e

solubility as

metal

of

a monitor

equilibrium

in o r d e r

recently,

et al

Fe/AI

segregation

employed

gas/bulk

by

densities.

surrounding

the

segregate

Podgurski,

of e n h a n c e d

such

to be

for must

of any

equilibria

have

temperatures. and h y d r o g e n equilibrium

However,

1063

employed,

should

dissolved

dissolved

temperatures

at r e l a t i v e l y

between

lower

to h a v e

atoms

is

Internal

is that

(i)

and e n e r g y

following

lattice.

to i n v e s t i g a t e

appear

probe

communication

for

dislocation

stress

been

conven-

recovery.

convenient

This

solute

measurement

for this

for r e c o v e r y only

nitrogen

(2)

are

metal.

nitrogen

surfaces.

have

as a p r o b e

large

to the

at r e l a t i v e l y

obtainable

273

excess

Direct

reason

Equilibrium at

excess

utilized

(5).

process.

in a d e f o r m e d

during

employed

not

the k i n e t i c s

which

changes

are

palladium

with

probes

techniques

interstitial

cores,

to i n t e r n a l

to d e f e c t s

recovery.

that

the

concerned few

commonly

these

recovery

K) c o n t a i n i n g

to d i s l o c a t i o n

been

but

in c o l d - w o r k e d

that

that

Other

solubility

demonstrated 773

1975)

concentration

the most

(3),

of the

of h y d r o g e n

to

activity

remarkably

defect

recovery.

stress

(673

30,

of m a c r o d i m e n s i o n a l

of t e n s i l e

presented

gates

of the

made

It is w e l l - k n o w n

alloys

are

has b e e n

microscopy

continuous

to r e g i o n s

research

there

monitoring

resistivity

use has b e e n

evolution such

the

of m e t a l s ,

June

even

has data

273

been

achieved

cannot

K is a low

be

ob-

enough

Inc

1064

HYDROGEN

temperature dium since

to be

SOLUBILITY

of some

Koster

interest

and Kehrer

of q u e n c h e d

and c o l d - w o r k e d

temperature

ranges

stitials)

dissolve

advantage

in the metal under

dissociates

(8).

Hydrogen

dom o c t a h e d r a l

(atom ratio)

hydride

phase

the low

two solid

phase

Figure

i.e.,

palladium

previous

vestigated

and these

solubility

of hydrogen

hydrogen

upon

Defects with

thickness,

into

were

brated

introduced

tures.

When

an

a non-stoichiometric

is completely

coexists

converted

over

this

palladium

ranges

to p~/2- in the region

im-

absorption

as w e l l - e s t a b l i s h e d .

in-

The of very

the d i s s o c i a t i o n

hydrogen

cleaned

by exposing

content,

of electronic

button

chips

of

CCI~

Samples

no further

manometers

Typically,

at 273 K and much

any

dosing

volume.

pressure

pressure

3 hours

time

evacuated

(in known

cali-

was n e e d e d

at greater

and

fall was

which had been

2 to

less

normally

were

the samples

from a known

cm,

and sealed

commencing

set of data points, when

(~99.95%)

(~ 0.01

machine

with

system.

of h y d r o g e n

for each

gauge.

small

the milling

were

vacuum

a palladium

into

of i0 -6 mm Hg before

obtained

pressures

established

a McLeod

pal-

that

for " w e l l - a n n e a l e d "

by h a n d c u f f i n g

to a vacuum

equilibrium

to the extent

in the e q u i l i b r i u m

i) d e m o n s t r a t i n g

(i to 2 grams)

from a series

in "well-annealed"

ii) over the t e m p e r a t u r e

(room temperature)

to successive

against

establish

(9).

ran-

in the metal.

Data were

the c o r r e s p o n d i n g recorded

(Figure

and m e r c u r y - f r e e

runs.

was

research

i0,

A) and also by o p e r a t i n g

the grease-

volumes)

(6,

is p r o p o r t i o n a l

machine

at room temperature

Equilibrium

occupying

is formed which

annealed role

data can be r e g a r d e d

The chips

absorption

of

its b e h a v i o r

is invariant

of h y d r o g e n

has been

in this

dissolution

Chips

B).

The

amounts

no detectable

lattice

latter

pressure

a detectable

data

contents

a milling

(chips

which

Data o b t a i n e d

agree with

small h y d r o g e n

play

(273 K),

the

hydrogen

the solubility

do not play

behavior.

e, until

large

the lattice

= 0.80

of inter-

region.

1 shows

perfections

phase,

equilibrium

over the

and that

defects

fcc p a l l a d i u m

studies

annihilation).

relatively

entering

H-to-Pd

occurs

9, No,

palla-

recovery

as a n n i h i l a t i o n

as vacancy that

is exceeded

(8) of c o m p o s i t i o n

The

recovery

where

upon

in the

of 0.009

content

to 8-phase.

conditions

interstices

H-to-Pd

of c o l d - w o r k e d

from their

at low temperatures

role

ladium;

that

and 473 to 570 K ( i d e n t i f i e d

is w e l l - e s t a b l i s h e d

with

shown

palladium

has the

VoI0

for r e c o v e r y

(7) have

300 to #00 K (identified

p a l l a d i u m / H 2 system hydrogen

IN P A L L A D I U M

to

tempera-

i0

Vol.

9, No.

I0

HYDROGEN

Typical chips

data

B are

shown

for s a m p l e s palladium

Data

B.

solubility

annealed

some

metal

and

within

metal

the

absorption within

is

therefore

(well-annealed) decreases enhanced

solubility

whose

was

also

to v a r i o u s

2, a n d

it is e v i d e n t

for t h e s e

samples

formation

(78%)

by

data

the

for the m o r e

cutting.

This

for the

tration

chips

minates

probably

results

solubility

at the

is n e g l i g i b l e

compared

ior was

noted

samples

the r a n g e bility

between

of d e f o r m a t i o n s

enhancement

was

The h y d r o g e n - f r e e in v a c u o The

hancement ther

and

results

the are

hydrogen

disappears

significant

chips

for

the

in

Figure

until

the

great those

of the

volume. at

subjected

redetermined

K.

eli-

resides

as

in b e h a v K. W i t h i n

78%,

after

the

solu-

of a n n e a l s each

one-half

K (12 hrs)

500

presence

samples

233

to a s e r i e s

Approximately 398

concen-

The

deformation.

8.

approximately

defect

cold-rolled

20% to

was

at

formed

78%.

273 K a n d

to the

de-

of the

No d i f f e r e n c e

cold-rolling,

an a n n e a l

of

as that

of h y d r o g e n

surface

(20%)

the

than

cold-rolled

amount

enhancement

as

that

pal-

in F i g u r e

degree

i.e.,

greater

proportional

(B) w e r e

following

recovery

by

solubility

solubility

almost

the

num-

of inter-

shown

fact

deformed

studied

are

from

much

the

limited

reproducibility

not

at

ratio

that

number

greatest

samples;

to t h e i r

directly

summarized

was

i.e.,

well-annealed

data

the

a significant

samples

enhanced

molecules

suggests

apparent

surface-

type atoms

modified.

The

with

enhancement

that

same

observed

of a very

a significant

the

the

enhancement

cold-rolling

observed

that

absorption

for w e l l -

large;

to a l a r g e

slightly

cold-worked

at d e f o r m a t i o n s

chemisorbed

rather

sample

enhancement severely

of

of h y d r o g e n

is

This

occupation

by

is

region

(cold-worked)/H-to-Pd

solubility

of d e f o r m a t i o n . there

of

that

The

cold-work

content.

only been

for the

the p o s s i b i l i t y

hydrogen

but

ob-

to d a t a

of h y d r o g e n

H-to-Pd

The

to the

sites

suggests

saturates

of a s i g n i f i c a n t

that

too;

trapping

ratio,

introduced

degrees

diffusion

fresh

chips.

hydrogen

have

data w e r e

similar

suggests

to the

from

subsequent

were

i.e.,

following

due

the

interstices.

1 mm Hg.

reactive

ladium

found

at

with

alter

cut

in the

which

cold-worked

is n o t

reactivity

Cold-work

octahedral

reproducible

were

identical

absorption

cases;

enhancement

slightly

of especially

stices

of hydrogen

due

not

1065

cold-worked

identical

removal

enhancement

is 1.77

only

chips

but

d i d not

the

remarkably

when

virtually

palladium

not

by

similar

in b o t h

of the

solubility

eg.,

of h y d r o g e n

occupy

solubility

K the

ber

to

micro-cracks

The 298

and

for c o l d - w o r k e d

is o p e r a t i v e

data were

later

(G-phase)

The k i n e t i c s

of process

The

A were

IN P A L L A D I U M

of h y d r o g e n

manner;

months

introduction

in the

isotherms.

i.

in t h i s

for c h i p s

The

absorption

in F i g u r e

prepared

buttons

tained. chips

for the

SOLUBILITY

anneal. of the

with

no

fur-

An a n n e a l

at

573

en-

1066

HYDROGEN

SOLUBILITY

IN P A L L A D I U M

Vol.

9, No.

I0

A FIGURE

A c o m p a r i s o n of isothermal abso r p t i o n data for c o l d - w o r k e d Pd ( c h i p s B) a n d w e l l - a n n e a l e d Pd.

i-

I

Open symbols: Chips B Closed symbols: well-annealed

I

nx,o '°

24

O ,•

273

K

A ,A

298

K

12

FIGURE

2

A c o m p a r i s o n of i s o t h e r m a l a b s o r p t i o n d a t a for c o l d r o l l e d Pd and w e l l - a n n e a l e d Pd, 323 K. •

, well-annealed

V

, 78%

deformed

, 49% d e f o r m e d

4

6

13 X 1 0 3

8

i I0

O

, 35% d e f o r m e d

X

, 18%

deformed

Pd

Vol

9,

No.

K (6 to

i0

HYDROGEN

hours)

1.15.

prolonged ture

resulted

The

of

Palladium 273

K (~ 0.i

vacancies for

Since

the

It

should

is

that

centration covery

to

the

of

erature

ubility Since

defects

eg.,

Kehrer noted

(7)

as

at

where

due

to it

field

the

an is

complexity

been it

they by

is

field.

suggested field

to

not

assign

to

play

that

A in

effect that of

the

arising the

energy

KSster from

of

and

the

or

brief.

conof

re-

solu-

a complement

the

B of

The

the

role

in

The

is

data, of

solubility

monitoring

of

dislocation

recovery.

which

are

not

in-

dislocaof

is

the

occurs

could

be

interstitials.

effect is

measurements

an

diffuse

which

are

resistivity

solu-

reduced

solubility Kehrer's

sol-

a consequent

If this

the

the

rearrangement with

studies

to

re-

the

plays

vacancies

array.

supplement

in

of

vacancies.

motion.

array

lita

data

where

stage of

the only

the

recovery

it

disappearin

range

elimination

enhanced

such

to

solubility

recovery

entire

that

as

annihilation

array.

leading

dislocation

is apparent

about

be

enhanced

this

a direct

their

hydrogen

stage

to

mon-

technique

type

annihilation

to

The

will

useful

temperature

the

a lower

enhanced

remarks

same

stage

stresses

(12).

for

correlations,

internal

The

of

demonstrate

difficulties

such

to

terpretation,

the

with

jog

reduced

analogous

the

dislocation

into

to

a tool

recovery

non-conservative

structure

is

to

proposed

K to

measurements

lead

Since

reasonable

the

is as

solubility

most

of

of

offered.

shown

1670

concentration

the

initiate

temperature,

stress

is

the

be

fraught

indirectly

altering

move

stress

a lower

Thus to

by

it

due

have

dislocation

lower

been

corresponds

here,

of

either

stage

the is

from

solubility

do n o t

has

interpretation

with

recovery.

a particular

of

tempera-

correspond

hydrogen,

the

might

during

low

a

Kehrer.

useful

resistivity

vacancies

technique

defects

recovery

then

of

Because

enhancement,

stress

this

The

ratio

after

enhancement was not observed

dissolve

influence

electrical

measurements

role

tions

that

quenched-in

direct

the

which

which

K.

communication

refleht

vacancies

jogs

this

advantage

bility

to

metals

and

a large

potentially

an

speculative

is

of

be

not

(i).

and

may

i000

only

trials.

does

specific

Koster

repeated

enhancement

quenched

introduce

that

assignment

covery

was

1067

removed

noted

Koster

mentioned

resistivity

ance

by

undoubtedly

Therefore,

The

to

purpose

is

was

A solubility

after

of

recovery

cm t h i c k n e s s )

defects

solubility

approximately

B noted

order

primary

of

do;

bility.

in

the

IN P A L L A D I U M

enhancement

the

palladium.

recovery

be

it

(0.01

solubility

of

at

of

A and

palladium

the

nature

stages

the

hydrogen

itoring the

bulk

second)

of

solubility

annealing

the

foil

into

quenched

that

of

where

temperatures

a reduction

remaining

period

ranges

in

SOLUBILITY

is

due

a correct a very

sensitive

in-

useful for

1068

HYDROGEN

SOLUBILITY

IN P A L L A D I U M

Vol.

9, No.

i0

ACKNOWLEDGEMENT The P e t r o l e u m Society

Research

Fund

is a c k n o w l e d g e d

administered

for the support

by the A m e r i c a n of this

Chemical

research

REFERENCES (i) W. Schilling, G. Burger, K. Isebeck and H. Wenzl, in "Vacancies and Interstitials in Metals," A. Seeger, D. Schumacher, W. Schilling and J. Diehl, eds., N o r t h - H o l l a n d , A m s t e r d a m (1969) p. 255. (2) H. Wenzl,

p. 363 in r e f e r e n c e

(3) M. Wilkens,

p. 485

i.

in reference

(4) H. H. Podgurski, R. A. 0riani 245, 1603 (1969). (5) J. D. Fast, "Interactions New York (1972).

i.

and F. N. Davis,

of Metals

and

Trans.

Gases,"

Met.

Barnes

and Noble,

(6) J. D. Clewley, T. Curran, W. A. Oates and T. B. Soc., Farad. Trans. I, 69, 449 (1973).

Flanagan,

(7) W.

(1965).

Koster

(8) F.A.

and H. Kehrer,

Lewis,

"The

Z. Metallkde.,

Palladium-Hydrogen

56,

760

System,"

AIME

Academic

J. Chem.

Press,

London

(1967). (9)

K. Skold

(10) E. Wicke (ii) J. Simons

and G. Nelin,

J. Phys.

and G. Nernst,

Bet.

and T. B. Flanagan,

(12) H. A. Wriedt

and R. A.

Chem.

Solids,

Bunsenges.

Oriani,

J. Phys. Acta

Phys.

28,

2369

Chem.,

(1967).

68,

Chem.,

69,

3773

Met., 18,

753

(1970).

224

(1964).

(1965).

1.5

FIGURE 3

1.0

Isothermal absorption data for cold-worked palladium after various annealings.

ol

.I-

E E .

• , unannealed

O.S

O,

Q.

12 hours at 398K , 6 hours at 573K

, well-annealed

01~ 0

2

3 n

4

5

6