Recovery of the electrical resistivity in Ta deformed at 4 K

Scripta METALLURGICA

Vol. 8, pp. 985-990, 1974 Printed in the United States

RECOVERY OF THE ELECTRICAL R E S I S T I V I T Y

Pergamon Press,

IN Ta DEFORI'~D AT 4 K

by H.A.Peretti + and G.Schoeck ++

Centro Atomico Bariloche, ktomica,

Universidad Nacional ++ ll.Phys.

Comision Nacional de Energia

Instituto de Fisica

Institut,

'Dr. Jose A. Balseiro',

de Cuyo,

Bariloche,

Argentina.

University of Vienna.

(Received May i0, 1974) i) Introduction

The increase information

in resistivity after cold-work

on the p r o d u c t i o n of point defects by moving dislocations.

Due to their tendency to brittle tions have been performed te~oerat1~rea. Nihoul

fracture

in Ta deformed

some results

(i) and

on the increase

at liquid helium temperature

on the d e f o r m a t i o n

measurements

especially at low

A ~evi~w of this work has been given by Schultz

sequent recovery up to room temoerathre. knowledge

very few such investiga-

in bcc transition metals,

(2). 2he present work reports

resistivity

and its recovery can give

and the sub-

The only other report to our

of bcc transition metals for resistivity

at this temperature

is by Goltz

2) Experimental

(3).

procedure

~he material was tantalum wire of 0.25 mm diameter from Wah Chang Corp.

of

The resistivity ratio for the as received material

985

was

Inc

986

RECOVERYOF ELECTRICAL RESISTIVITY IN Ta DEFORMED AT 4K

~=

R(2~3

K) / R(4 K) ~ 2 0 .

ves as n o s s i b l e Si<100,

substitutional

Jn ~ d y n a m i c

impurities

for 15 min.

oxygen ~ t m o s o h e r e

then t h e y were d e g s s s e d

a v a c u u m of 2 x 10 -9 Torr.

size effect

Some

W<200,

~

(5) may have

value

were

and t e m D e r s t u r e

pressure

at a t e m p e r a t u r e

Fe
of ~ 2 x 10 -5

of about 3.000 ~C at

(~). A f t e r this p r o c e d u r e

reduced

for b u l k m a t e r i a l

of the samples

pressure

the r e s i s t i v i t y

Due ~o the small d i a m e t e r s

the m e a s u r e d value

so that c h a r a c t e -

i n t e n t i o n a l l y d o p e d w i t h oxygen, being regulated

210 to 2z~O; w h i c h c o r r e s o o n d s

the

c o u l d be hJ~her.

to ~

the p a r t i a l

a c c o r d i n g to the results

v e n by F r o m m and d~hn (6]. The r e s i s t i v i t y ratio ~

Ti<150,

lea-

st a te~!p~rature of 1.800 2C

w i t h partial

ratio was b e t w e e n 1.200 and 1.700.

ristic

g i v e n in 'less t h a n ppm'

8,

all others b e i n g < 2 0 ~pm.

~he wires were d e c a r b u r i z e d

Torr.~

An analysis

Vol.

of these

gi-

s;Lm!)les w~ms

oxy
i00 ppm (7).

The d e f o r m a t i o n

of the wire s~mple~ was made by r o l l i n g

For this p u r p o s e nical

a loon of Ta wire was i n s e r t e d into a c o m m e r c i a l

r o l l e r - b e a r i n ~ w h i c h wn~ t~irne~ while

direction.

Values

Details

a n n ] y i n ~ a force

of the t e c h n i q u e

ter t e c h n i a u e

and d 2 its t h i c k n e s s

are d e s c r i b e d

elsewhere

ih. p r e c i s i o n

r e s i s t i v i t y was m e a s u r e d w i t h the s t a n d a r d u s i n ? a Leeds

_

The su-

m a g n e t i c field.

was b e t t e r t~an + 0 , 0 5 O / o and the ,.

--

r e s i s t i v i t y chancre was i x i0 -II

factors for c o n v e r s i o n

into s p e c i f i c

cm. 2ne geome-

r e s i s t i v i t y were o b t a i n e d

by meas'~rin~ the r e s i n t i v i t 3 ~ at room tem~eratu_~'e b e f o r e f orm~ ti on.

potentiome-

~nd liortllruD K 5 p o t e n t i o m e t e r .

of the m e a s u r e m e n t s

smallest detectable trical

after rol-

(~).

p e r c o n d u c t i n g state was d e s t r o y e d by an a p o r o D r i a t e e

in axial

of ad/d up to 90°/o could be o b t a i n e d w i t h o u t f r a c t u r e .

The e l e c t r i c a l

~n

co-

The d e f o r m a t i o n was m e a s u r e d by Ad/d = ( d l - d 2 ) / d I where d I

is the o r i g i n a l diL~meter of the wSre ling.

in liquid He.

and after de-

No.

8

Vol.

8, No.

8

RECOVERY OF ELECTRICAL

The temperature

RESISTIVITY

was measured by two copper-constantan

spot-welded to the sample.

Temperatures

in the cryostat to various

above the He level. A copper shielding

vided temoerature highest

homogeneity

thermocouples

above licuid helium tempera-

ture were obtained by raisinm the sample heights

IN Ta D E F O R M E D AT 4K

around the sample pro-

and a calefactor helped to reach the

annealing temperatures.

The isochronal

annealin~

time was always iO min.

sample was kept at a fixed temperature

~@ithin this time the

within a range of 3 1 K

up to

i0 K, within 3 0,5 K u~ to 200 K and within ~ 0,5 K uo to 300 K.

3) Results

The technique

described

than hitherto

obtained

it was only possible before

fracture

increase

above allows deformations in bcc transition metals.

to reach a plastic

~Jhereas by torsio~

strain of Cmax
of a ~ up to 9 x lo-S]~cm.

were up to now only obtained

tron (i0, ii) irradiated Alp for the various increase

at ~ K much larger

at 4 - K

(5), the values here were Ad/d uo to 50°/O with an

in resistivity

such magnitude

and Discussion

samples.

samples.

Values

in neutron

of 6 ~ of

(9) or elec-

Fi~.l shows the original

increase

The oxygen doped s~
A~o for the same d e f o r m a t i o n than the piJre ones. The saee

result is also observed temperature

for small and medium deformation

at room

(12). A similar observation was a]so made in neutron ir-

radiated samples

(9) where

also the oxygen doped samples

showed a

larger damaging, rate.

Fig.2 shows the annealin~

curves

ture of 300 K there exists little pronounced

for all samrAes.

a conbinuo~s

annealing stares.

about 350/0 of the original

Up to the tempera-

recovery with verTf small and

At the temperature

&~o have annealed

of 300 K only

out. This is less than

987

988

RECOVERY OF ELECTRICAL

the values

less than in irradiated samoles where

of Ag o have annealed

A typical example

Vol.

samples

temperature

recovery occuring

in the irradiated samples In the interpretation

there exist some

of the electron irra-

around 17 K and that the recovery stage

around 160 K m a y be attributed to the dissolution No such distinct

impurities

of complexes

impure and may have contained

there exists the possibility that intersti-

tials were trapped and continuously released during warm-up. p o s s i b i l i t y is however that very few interstitiais at low temperature

deformation.

deformation

of in-

stages are observed after deformation.

Since the material used here was more also metallic

over the whole

of Faber et al (ll) it is assumed that free inter-

in Ta become mobile

terstitials.

and

is shown in Fig.3. As can be seen in the deformed

range whereas

diated experiments

about 80O/o

of the relative recovery A~/A~o for deformed

distinct recovery stages.

temperature

8, No.

out at this temperature.

samples there is a nearly continuous

stitials

IN Ta DEFORMED AT 4K

of Goltz (3) who reported that about 60°/o have annealed

and considerable

irradiated

RESISTIVITY

Another

are formed in Ta

It has already been observed

(13) that the resistivity increase

at room

in Ta (and

Nb) is much less than in W and No. A low production rate of interstitials could be rationalized by observing that ooint defects med by jogs in moving screw dislocations less mobile

and these become

are for-

less and

at low temoerat~Jres.

Acknowledgment

One of us (H.A.P.)

is grateful for financial

Nacional de Investigaciones

Cientificas

supoort by the Consejo

y Tecnicas

of Argentina.

8

Vol.

8, No.

8

RECOVERY OF E L E C T R I C A L

RESISTIVITY

IN Ta D E F O R M E D AT 4K

References: i) H. Schu]tz, iiat.Sci.En[~. ), 189 (1965/69). 2) J. 1,1noul in: Vacancies and Interstitials in He¢als (A. See~er e t a ] ed), North Ho]land l~bl.Comp. 1970, n. 859. %) G. Goltz, Diplomarbeit, University of Stuttgart, 1971. 4) D.P. Seraohim, J.l. Budnick and W.B. Ittner III, Trans.AIHE _218,

527 (1960). 5) E.il. Sond~eimer, Adv. Phys. I, i (1952). 6) E. Fromm and H. Jehn, Vacuum 19_, 191 (1969). 7) G. iiorz, rE. Gebhardfi and W. D~rrschnabel, Z. iuetallk.

56, 9.5z~

(1965). 8) H.A. Peretti, Inf. Centro k¢omico Bariloche CAB ig_ (1971). 9) G. Buri~er, K. Isebeck, R. ~£erler, J. Volkl, H. Wenzl, H.H. Kuhlmann and H. Schultz, Phys.Let. 20, 470, ~72 (1966). I0) D. ~ueissner and W. Schilling, Z. Naturforschunm 26 a, 502 (1971). ii) K. Faber, J. SchweJkhardt and H. Schultz, Verhandl. DPG VI 8,

746 (1974). 12) A. Kothe and F. Schlat,

Phys.Stat.Sol.

15) E. Krautz and H. Schultz,

21,

K 75 (1967).

Z. an~ew. Physik 1_5, i (1965).

Figures:

o,e ÷

0.6 @

÷

o.~

o,2

~ ~ -"/ 0,I

Fix. i.

Increase

d, (~d

z

0,2

0,3

oxigen-doped (~30 ppm) 0.4

in resistivity with deformation.

0,5 -~

989

990

RECOVERY OF ELECTRICAL

RESISTIVITY

IN Ta DEFORMED AT 4K

Vol.

8, No.

:o'

so so - -

200

Fig.

2.

]

~

50'

100 '

Recovery various

150 '

200 '

of resistivity

'

~

of o~re,

T(K) 3 0

and O-doped

samples with

deformations.

•-. so. ~

lplast, def.

0.~1~ \ ~

50%

l

60

1700

le

3°_,.°°.

,o°v,

,3~

28oo

[3]

3200 ?,~0o

[11]

[9]

0.6

O.2

,;o Fig.

3-

Comparison work.

2;0 of recovery curves

3~o

"~-T--,

,oo

-

TO.)

after irradiation

and cold

8