1019 1020 10211E17

1E18

1E19

1E20 NRA (15 m layer) TDS (200 m sample)

NRA*200/15

Deu

teriu

m re

tain

ed, D

/cm

2

Fluence, D/cm2

1019 1020 1021 10221E15

1E16

1E17

1E18

1E19

1E20

100 eV D+ plasmaRT-700 K, 200 m gas, RT, 200 mafter 1 h Ar cleaning[2], 1.7 keV D+

380 k, 250 m[4], gas at constant cleaning,380 k, 250 m

Deu

teriu

m re

tain

ed, D

/cm

2

Fluence, D/cm2

1. Ti, V, Cr – consecutive elements of IV period of the periodic table of Mendeleev2. V-4Cr-4Ti

3. Ti, V – hydrogen getters (in a sertain conditions can pump out hydrogen)V-4Cr-4Ti - ?

3.2. If Ti is a main component of getter, Cr and V reduce activation temperature4. Some publications discuss hydrogen retention in V-4Cr-4Ti alloys of Russian and Japanese production [1-3].4.2. Hydrogen retention properties of two V-Cr-Ti alloys of the same composition

may noticeably differ5. Hydrogen retention properties of Bochvar’s V-Cr-Ti were never investigated

Hydrogen Retention Properties of V-4Cr-4Ti Alloy

A.V. Golubeva1 , A.V. Spitsyn1, N. Bobyr1, M. Mayer2, V.S. Efimov 3, Yu. M. Gasparyan3, D.Yu. Smirnov1

1 – NRC ‘Kurchatov Institute’, Ac. Kurchatov sq., 1/1, Moscow RU-123182, Russia.2 – Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstrasse 2,D-85748 Garching, Germany. 3 – National Research Nuclear University "MEPHI", Kashirskoe sh.31, Moscow 115409, Russia

1.1. introduction

2. Material

3. Interaction with gas (getter properties)

5. Conclusion

New constractive materials – low-activated, with good thermomechanial properties are required for next-step fusion devices (DEMO reactor, fusion neutron sourses)

V-Cr-Ti alloys - promising constructive materials (vacuum chamber, lithium blanket).

In the Bochvar Institute (Russia) a base V-4Cr-4Ti was produced with goodthermomechanical properties that would allow it’s use in fusion devices. The hydrogen interation with the material – a critical safaty question – was never investigated before.

In the resent work hydrogen retention in V-4Cr-4Ti alloy was investigated at gas loading and plasma irradiation.

V 92.0

Cr 3.0

Ti 4.3

Fe 0.002

Mn <0.0005

Ca 0.043

Mg <0.004

Chemical analysis SEM

0.2 mm thick hot-rolled V-4Cr-4Ti foil

1.2. What is known about H – V-Cr-Ti interaction?

Can dissolve H very good:(Nb:H – up to 1:2)

Heated form hydrides(Ti:H – up to 1:1)

Decrease swelling &hydrogen embrittlement

Improves strength &corrosion stability

One of the most hard materials(second after W)

4. Deuterium plasma irradiation

Typical sorption curve

Experiment

1. P0= 1 10-7 Torr2. Sample is cleaned in Ar glow discharge (several hours, 400 V, 0,1 mА/cm2)3. Sample is annealed up to 7500 С (0,5-8 hours) and cooled down to RT4. Pumping is stopped. Hydrogen fills chamber up to 110-4 torr5. Pressure decreases due to sorption by sample

0 500 1000 1500 2000

2

4

6

8

10

P H2,

10-5

Tor

r

Time, s

pumped deuterium

as reseivedanealing at 1023 K, Ar+ plasma cleaninganealing at 1023 K, Ar+ plasma cleaning, air exposure

sample 40500,2 mm (0.4 cm3)after activation (glow discharge cleaning & annealing at 1000 K for 8 hours)

Under certain conditions(clean surface, advance annealing)

V-4Cr-4Ti surface may act as a getter pump (sorbing hydrogen)

Deuterium capture as function of advance annealing

0 2 4 6 80.0

2.5

5.0

7.5

10.0

Deu

teriu

m re

tent

ion,

1016

D

Duration of advanced annealing, hours

510-3 at.%

4.1. ExperimentalInvestigation of retention:NRA (Nuclear Reaction Analysis) TDS (thermodesorption)

Plasma irradiation (PIM installation):Plasma composition: 70% - D3+;

20% - D2+; 10% - D+ ,

Accelerating potential: -300 V.Plasma density: 6·1010 cm-3

Fluence: 1019-1021 D/cm2

Pressure: 5·10-4 TorrTemperature: 290 – 600 К

• Total retention• States of H in material

• Retention in near-surface layer (up to 15 m)

3He+ or 3He2+

0.7÷5.5 MeVα, p

D+3He4He+p.

4.2. Deuterium retentionNRA

Depth profiles

0 2 4 6 8 10 12 14 16

0.00.51.01.52.02.53.03.54.04.55.05.56.0

D c

once

ntra

tion,

at.%

depth, m

5 min, RT, plasma 1 h, 65 0C, plasma 6.5 h, 170 0C, plasma 1 h, 210 0C, plasma 1 h, 305 0C, plasma 6 h, 327 0C, gas, P=1*104 Pa 1h, RT, plasma, floating potential

• Deuterium penetrates deep in the material• Depth distribution is almost uniform

Fluence dependence (1019-1021 D/cm2, temperaturesRT-570 K)

• In a range RT-570 K temperature does not influence retention significantly• At a fluence 1021 D/cm2 saturation is not achieved

TDS

5 at.%

Logarithmic scale:• TDS shape is typical for V-4Cr-4Ti• Desorbs mainly as D2

Linear scale: Symmetric peaks (second order desorption)

TDS after exposure in H2 gas, 80 Pa, 3 hoursRussian V-4Cr-4Ti of previous generation

[1]

Typical TDS of plasma-irradiated V-4Cr-4Ti

Retention from plasma & gasup to 8 at.% D

• At plasma irradiation retention much higher than at gas exposure can be achieved

anna-golubeva@yandex.ru

Hydrogen retention in V-4Cr-4Ti (Bochvar institute production) at gas loading and plasma irradiation has been investigated for the first time• V-4Cr-4Ti under certain conditions (clean surface, advance annealing) may act as a hydrogen getter pump (sorbing hydrogen)• H retention in Bochvar’s alloy is comparable with retention in Japanese analogs• At plasma irradiation hydrogen accumulation may be orders of magnitude higher than at gas loading• V-4Cr-4Ti accumulates huge amount of deuterium (5 orders higher than ferritic steel RUSFER at the same condition)• In case of use of V alloys as a constructive material for fusion, barrier coating for decreasing of hydrogen migration through and retention in V-4Cr-4Ti are absolutely necessary Retention in V-4Cr-4Ti

and RUSFER (ferritic steel)

Use of V-4Cr-4Ti as a fusion constructive material of the first wall without barrier coating is impossible

0.0 5.0x10 20 1.0x10210

1

2

3

4

5

6

Deu

teriu

m re

tain

ed, 1

018D

/cm

2

Fluence, D/cm2

In a near-surface layer 15 m deep

6. AcknowledgmentThis work was supported by the Impuls- und Vernetzungsfond der Hemholtz Gemeinschaft e.V.,Russian Foundation for Basic Research grants Nr 11-02-91322 and Nr 11-08-01069, Russian President grant for young scientists MK-2839.2011.2

500 K

RT-300 K

1 – A. Kh. Klepkov et. Al, Hydrogen release from irradiated vanadium alloy V–4Cr–4Ti // Fusion Engineering & Design 51-52 (200) 127-1332 – J. Masuda et al. Diffusion and trapping of tritium in vanadium alloys, JNM 363-365 (2007) 1256-12603 – Y. Yamauchi et. al, Deuterium retention in V–4Cr–4Ti alloy after deuterium ion irradiation, JNM 329-333 (2004) 397-4004 – Y. Hirohata et al, Deuterium and helium retentions of V–4Cr–4Ti alloy used as first wall of breeding blanket in a fusion reactor, JNM 348 (2006) 33–39

2 K/s

3- 5 orders of magnitude difference!

TDS data

TDS after irradiation by 1.7 keV D ionsNIFS-HEAT-1 (Japanese V-4Cr-4Ti)

[2]

Comparison of two methods up to 8 at.% D

At plasma irradiation:• Results of two methods at elevated temperatures (fluence 1020) are very close• Deuterium is distributed uniformly through the sample

Oxide layer strongly decreases hydrogen sorption

7. References

NRC“KURCHATOV

INSTITUTE”