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Cavity formation and growth during pulse high heat loading in nickel implanted with helium or deuterium ions
joaro.alof flgcIgar tutorials
Journal of Nuclear Matertals 191-194 (1992) 1248-1253 Nortb-Hol:and
Cavity formation and growth during pulse high heat loading in nickel implanted with helium or deuterium ions T. Muroga ", K. Dohi b, y. lshihama b, K. Tokunaga" and N. Y o s h i d a "' "Research blstttute for Apphed Mechamcs, Kyushu Um~ersay, Kasuga, Fultuoka 816, Japan
t, lnterdasctphnary Graduate School of Engmeer,ng .~wnces, Kyushu Umt,erstty, Kasuga, Fukuolta 816, Japan
Pulse and steady-state heating effects on the mlcrostructure of mckel implanted with helium or deutermm ions have been mvestlgated, m order to examine the combined effects of parUcle bombardment and heat loading on the plasma-facmg components of fulton reactors. Large dlmensmnal changes of the plasma-facing surfaces due to bubble growth is expected when they are implanted with hehum or hydrogen isotopes and then pulse heated Gram boundary degradation may be small, however, for the case of pulsed heating because of the small accumulation of bubbles at the gram boundartes
!. I n t r o d u c t i o n Plasma-facing materials of fuston reactors are subject to high flux particle thelium, hydrogen ~sotopes
a n d n e u t r o n ) irradiations a n d high pulse (or steady) heat loading. As a basic study of the particle implantation effects, microstructural evolution d u r i n g helium [1-3] a n d h y d r o g e n (or d e u t e r i u m ) [4,5] i m p l a n t a t i o n
11 OMW
310MW
Fig 1 Bubbles formed by a pulse heat loading with different power to mckel implanted wtth 5 keV helium tons to 3 × 10-'t/m 2 0022-3115/92/$05 DO © 1992 - Elsevier Science Pubhshers B V All rights reserved
T Muroga et al. / Heaung effects m He- or D-tmplanted Ni
1249
has been investigated in nickel, stainless steels and other materials under various ~rradiation conditions. Post irradiation annealing experiments have also been carried out to elucidate thermal stabihties of defect clusters such as dislocations and bubbles, and helium(hydrogen) release behavior [3-8]. However, pulse heating effects on the defect evolvtion have not been well invesugated Pulse heating effects have been examined by a number of groups using charged particle or laser beams (e.g. refs. [9,10]). The major interests have been surface erosmn or particle emissmn. Very httle information ~s, therefore, available on the combined effects of the particle implantatmns and the heat loading. In particular, a mechanistic study of mlcrostructural evolution during pulse heat loading has been scarce. This is the objective of the present paper.
(2) Steady-heat loading (973-1273 IL 1 h) carried out in a vacuum furnace. (3) Combined heat loading (steady loading followed by pulse loading). The ruby laser used for the pulse heat loading was described in our previous papers [11,12]. According to a quick response thermo-spot sensor, the surface temperature was elevated to about 1400°C for 1 to 1.5 ms during the pulse heat loading. Evidence of surface melting was observed above 540 M W / m 2. Such a condition is beyond the scope of the present experiments. After the heat loading, the specimens were backthinned and microstruetures were observed with a transmission electron rr,iemqcopc.
2. Experimental
3.1. Bubble formatton and growth m hehum-lmplanted mckel
Well-annealed, 99.99% pure nickel speomens were implanted with 5 keV helium or deuterium runs to 3 × 1021/m 2 at room temperature, succeeded by the following three ty[ es of heat loading. (1) A pulsed heat loading (110-420 M W / m 2, 1 ms) by a laser shot.
3. Results
In helium-implanted speclmer~s, large bubbles were observed m all cases of heat loading. Figs. 1, 2 and 3 show microstructures after pulse, steady and combined heating, respectively. In the case of pulse heating, the bubble size rapidly increases with increasing heat load
Fig 2. Bubbles formed by a steady heating for 1 h to mckel implanted with 5 keV hehum ions to 3x 1021/m 2
T Muroga et at
1250
/ Heating effects an He- or D-tmplanted Nz ~ , ~
110MW/m 2
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Ftg 3. Bubbles formed by a combined heat loading (steady heating at 1073 K for 1 h followed by a pulse heating wroth different power) to mckel implanted with 5 keV helium sons to 3 × l0 zu/m e
denmty. Elongated cavitnes were observed only m the case of pulse heating. Thns could be the initial stage of bubble coalescence, whnch was promoted dnrmg the heating and then frozen-in durmg the succeeding coolrag. In the case of combined heating, additional bubble growth occur durmg the sueceedmg pulse heatmg The total bubble volumes for these three cases are compared in fig. 4. The figure shows that the bubble
volume can be very large for the pulse heating relative to that for steady heatmg or combined heating. Fig. 5 shows the re!atnon between the depth and the raze of bubbles for the three cases as determined by the stereoscopxc observation techmque. In the case of pulse heating, very large bubbles were formed around the
128 ~ A
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0 Pulse Loser 3SOMW/m2 • Steady Heobng. 1073K [] ifeotlv~a 1073K + Loser 350MW/m2-
6C
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200 260 310 350 420 975107311731275)K 200 260 510 550 420 Cuw/m2) (uw/~) Annealed for lh Annealed on 1073K for lh, Loser Shot at R T Loser Shot at R T
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Fig. 4 Total bubble volume per observed area for the three heating cases
Frog 5 Relatmn between the depth and the size of bubbles for the three cases of heating determmed by a stereoscopic observatton technique Note that the maximum image extenmon Is measured fm elongated bubbles
T Muroga et al / Heating effects m He-or D-unplanted IV:
ion deposition range and tiny ones, which were not observed in either steady or combined heat loading, were formea at deeper area~ of the specimens. The size range of bubbles was narrow and indepcndent of the d;stance from the surface in the ease of steady and combined heat loading. Fig. 6 compares bubbles m the vicinity of the grain boundaries for the pulse and the steady heating. Accumulations of bubbles at grain boundaries, which is promment in the case of steady heating, is not observed in the case of pulse heating.
3.2. Bubble formation m deuterium-implanted nickel
In deuterium-implanted specimens, bubbles were observed only in the case of pulse heat loading as shown in lig. 7. Fig. 8 shows the depth and size of bubbles for the case of pulse beating in deuterium-implanted mckel compared with those in helium-implanted nickel reproduced from fig. 5. The difference m the bubble depth distribution correlates with the difference in the ton deposition profile.
1251
4. Discussion The pulse heat load effects observed in the present experiment seem to be caused by the fact that the diffusion of helium (deuterium) during heating was small because of a very short heating time. The instantaneous gas pressure however becomes extremely high because of the very high temperature. Some unique features of the microstructure observed in the case of pulse heat loading, i.e. the elongated bubbles shown in fig. 1, coarsened bubbles around the ion range region m fig. 5, and no bubble accumulation at grain boudaries shown in fig. 6, can be explained by the above reasoning. A thermal desorption spectroscopy of helium implanted into nickel [8] showed that at an implantation fluence of arouna 3 x 102t/m 2, the helium release starts at 1000 to 1100 K. This is in good agreement with the present steady heating experiments, in which bubble coarsening starts at 1073 K. The good correlation between the bubble depth distribution and the ion deposition profile, shown in figs. 5 and 8 suggests that the distrtbution of bubbles
Fig 6 Bubbles in the vtomty of a gram boundary for (a) the pulse and (b) the steady heating cases
1252
T Muroga et al / Heating effects
'~n
He- or D-implanted Nt
Fig 7 Bubbles formed by a pulse heal loading with different power to nickel implanted with 5 keV deutermm ions to 3 x l021/m 2.
formed dunng the pulsed heating should reflect the nascent distribution of the implanted helium or dcutermm. Thus the present pulse heating may be used as a tool to measure the distribution of implanted tons in the specimen.
120
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I
o
I oo
'
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30
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o He =mplontecl • D rmplonted
The present results provide mstght on the effects of a high pulsed heat load on plasma-facing components. Large dimensional changes due to bubble growth are expected when helium or hydrogen isotopes are implanted in plasma-facmg components, where the temperature ts mamtained relatively low, and then pulse heated Grain boundary, degradation may be small, however, in the case of pulse heat Ioadmg because of the small accumulation of bubbles at the gram boundaries.
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5. Conclusion
I ~II"
50 Depth (nrn)100
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Fig 8 Relation between the depth and the size of bubbles for the case of pulse heatmg m deutenum-implanted nickel compared with those m helium-implanted nickel reproduced from fig 5
Pulse high heat Ioadmg aeter hehum or deuterium implantation can lead to s,..rious bubble coarsemng Large dimensional changf':s are expected m the plasma-facmg surfaces when helium or hydrogen isotopes are implanted and then pulse heated. Grain boundary degradation may be small, however, m the case of pulse heat loadmg because of small accumulation of bubbles at the grain boundaries.
T Muroga et al / Heating effects m He-or D-tmplar, ted Nt
References [1] W. Jaeger and J Roth, J Nucl. Mater 93 & 94 (1980) 756 [2] P.B. Johnson and D J Mazey, J Nuel. Mater, 93 & 94 (1980) 721 [3] K. Niwase, T Ezawa, T Tanabe and F.E FujIta, J Nucl. Mater. 160 (1988) 229 [4] N Yoshlda, N. Ash,zuka, T Fujiwara, T. Kantd and T. Muroga, J Nucl Mater 155-157 (1988) 775 [5] N. Yoshldd, T Kurita, T Fujiwara and T Mnroga, J. Nucl Mater 162-164 (1089)1082. [6] N. Marochov, L J Perryman and P J Goothew, J Nuel Mater. 149 (1987) 296
1253
[7] V N. Chernikov, H Trmkaus, P. Jung and H. Ultmaier, J. Nucl. Maler. 170 (1990) 31. [8] V.F Zelensk,j, I.M Neklyudov, V V. Ruzhitsk,j, V.F. Rybalko, V.I Bendikov and S.M. Kha~an, J Nuci. Mater. 151 (1987) 22 [9] V. Phdipps, E. Vietzke, M. Erdweg and K. Flaskamp, J Nucl. Mater. 145-147 (1987) 292. [10] J G. van der Laan, J. Nucl. Mater. 162-164 (1989) 964. [11] H Kamezdkl, K. Tokunaga, S. Fukuda, N. Yoshida and T. Muroga, J Nucl. Mater. 179-181 (1991) 193. [12] T Muroga, H. Kamezaki, K Tokunaga and N. Yoshida, J Nucl. Mater 176 & 177 (1990) 450.
Journal of Nuclear Matertals 191-194 (1992) 1248-1253 Nortb-Hol:and
Cavity formation and growth during pulse high heat loading in nickel implanted with helium or deuterium ions T. Muroga ", K. Dohi b, y. lshihama b, K. Tokunaga" and N. Y o s h i d a "' "Research blstttute for Apphed Mechamcs, Kyushu Um~ersay, Kasuga, Fultuoka 816, Japan
t, lnterdasctphnary Graduate School of Engmeer,ng .~wnces, Kyushu Umt,erstty, Kasuga, Fukuolta 816, Japan
Pulse and steady-state heating effects on the mlcrostructure of mckel implanted with helium or deutermm ions have been mvestlgated, m order to examine the combined effects of parUcle bombardment and heat loading on the plasma-facmg components of fulton reactors. Large dlmensmnal changes of the plasma-facing surfaces due to bubble growth is expected when they are implanted with hehum or hydrogen isotopes and then pulse heated Gram boundary degradation may be small, however, for the case of pulsed heating because of the small accumulation of bubbles at the gram boundartes
!. I n t r o d u c t i o n Plasma-facing materials of fuston reactors are subject to high flux particle thelium, hydrogen ~sotopes
a n d n e u t r o n ) irradiations a n d high pulse (or steady) heat loading. As a basic study of the particle implantation effects, microstructural evolution d u r i n g helium [1-3] a n d h y d r o g e n (or d e u t e r i u m ) [4,5] i m p l a n t a t i o n
11 OMW
310MW
Fig 1 Bubbles formed by a pulse heat loading with different power to mckel implanted wtth 5 keV helium tons to 3 × 10-'t/m 2 0022-3115/92/$05 DO © 1992 - Elsevier Science Pubhshers B V All rights reserved
T Muroga et al. / Heaung effects m He- or D-tmplanted Ni
1249
has been investigated in nickel, stainless steels and other materials under various ~rradiation conditions. Post irradiation annealing experiments have also been carried out to elucidate thermal stabihties of defect clusters such as dislocations and bubbles, and helium(hydrogen) release behavior [3-8]. However, pulse heating effects on the defect evolvtion have not been well invesugated Pulse heating effects have been examined by a number of groups using charged particle or laser beams (e.g. refs. [9,10]). The major interests have been surface erosmn or particle emissmn. Very httle information ~s, therefore, available on the combined effects of the particle implantatmns and the heat loading. In particular, a mechanistic study of mlcrostructural evolution during pulse heat loading has been scarce. This is the objective of the present paper.
(2) Steady-heat loading (973-1273 IL 1 h) carried out in a vacuum furnace. (3) Combined heat loading (steady loading followed by pulse loading). The ruby laser used for the pulse heat loading was described in our previous papers [11,12]. According to a quick response thermo-spot sensor, the surface temperature was elevated to about 1400°C for 1 to 1.5 ms during the pulse heat loading. Evidence of surface melting was observed above 540 M W / m 2. Such a condition is beyond the scope of the present experiments. After the heat loading, the specimens were backthinned and microstruetures were observed with a transmission electron rr,iemqcopc.
2. Experimental
3.1. Bubble formatton and growth m hehum-lmplanted mckel
Well-annealed, 99.99% pure nickel speomens were implanted with 5 keV helium or deuterium runs to 3 × 1021/m 2 at room temperature, succeeded by the following three ty[ es of heat loading. (1) A pulsed heat loading (110-420 M W / m 2, 1 ms) by a laser shot.
3. Results
In helium-implanted speclmer~s, large bubbles were observed m all cases of heat loading. Figs. 1, 2 and 3 show microstructures after pulse, steady and combined heating, respectively. In the case of pulse heating, the bubble size rapidly increases with increasing heat load
Fig 2. Bubbles formed by a steady heating for 1 h to mckel implanted with 5 keV hehum ions to 3x 1021/m 2
T Muroga et at
1250
/ Heating effects an He- or D-tmplanted Nz ~ , ~
110MW/m 2
,~.~ I _ _ ~
r
31 +
t
.)
'
i'
"
=
41, +
+
•
• ,~
+
I*
+
+~ •
•
--
-
-
.\..
.
•,
.
.I)
~+,
.
", o
+
•
),
•.
;
•
)
....
.
+
•
!,
" ~,
•
•
, I1•1 b IDO •
,I
,;'" O
I
•
, ~)
-
.'. ":;.. •
+, I, 'O .i+
II
I1+
. 411
•
,. +
•
.++
d
++
+
""
41 +"
)")
,o •
.,
~+ )
II
k+•
:
~
t
O'm,
oe- O o~O.• ~) •
O•
a) ,,O
•
•
-~
p ..•
" •
g
'
o, .....
•
•,
.o.>•~,+
Ftg 3. Bubbles formed by a combined heat loading (steady heating at 1073 K for 1 h followed by a pulse heating wroth different power) to mckel implanted with 5 keV helium sons to 3 × l0 zu/m e
denmty. Elongated cavitnes were observed only m the case of pulse heating. Thns could be the initial stage of bubble coalescence, whnch was promoted dnrmg the heating and then frozen-in durmg the succeeding coolrag. In the case of combined heating, additional bubble growth occur durmg the sueceedmg pulse heatmg The total bubble volumes for these three cases are compared in fig. 4. The figure shows that the bubble
volume can be very large for the pulse heating relative to that for steady heatmg or combined heating. Fig. 5 shows the re!atnon between the depth and the raze of bubbles for the three cases as determined by the stereoscopxc observation techmque. In the case of pulse heating, very large bubbles were formed around the
128 ~ A
-
0 Pulse Loser 3SOMW/m2 • Steady Heobng. 1073K [] ifeotlv~a 1073K + Loser 350MW/m2-
6C
o
o"
-i ~
200 260 310 350 420 975107311731275)K 200 260 510 550 420 Cuw/m2) (uw/~) Annealed for lh Annealed on 1073K for lh, Loser Shot at R T Loser Shot at R T
°o o •
mt
"
A&
c)
•
Comb)ned Heating
N 2C
o
%®
-,~ 4C Steady Heating
20~
o
o
lO-
0
o
~o
.~ 8a
15-
o
"--
0 o
Pulse Heatung
;~ ~
3
2O
AA
-
o_~
..o A. ~
0
0 ~k
-'!.o~ ,.p,~ o oo o
&O
o.~o
-
o"
(~k
•
• • Ooo
50 Depth (nm) I00
-
o•
IO
15(
_
Fig. 4 Total bubble volume per observed area for the three heating cases
Frog 5 Relatmn between the depth and the size of bubbles for the three cases of heating determmed by a stereoscopic observatton technique Note that the maximum image extenmon Is measured fm elongated bubbles
T Muroga et al / Heating effects m He-or D-unplanted IV:
ion deposition range and tiny ones, which were not observed in either steady or combined heat loading, were formea at deeper area~ of the specimens. The size range of bubbles was narrow and indepcndent of the d;stance from the surface in the ease of steady and combined heat loading. Fig. 6 compares bubbles m the vicinity of the grain boundaries for the pulse and the steady heating. Accumulations of bubbles at grain boundaries, which is promment in the case of steady heating, is not observed in the case of pulse heating.
3.2. Bubble formation m deuterium-implanted nickel
In deuterium-implanted specimens, bubbles were observed only in the case of pulse heat loading as shown in lig. 7. Fig. 8 shows the depth and size of bubbles for the case of pulse beating in deuterium-implanted mckel compared with those in helium-implanted nickel reproduced from fig. 5. The difference m the bubble depth distribution correlates with the difference in the ton deposition profile.
1251
4. Discussion The pulse heat load effects observed in the present experiment seem to be caused by the fact that the diffusion of helium (deuterium) during heating was small because of a very short heating time. The instantaneous gas pressure however becomes extremely high because of the very high temperature. Some unique features of the microstructure observed in the case of pulse heat loading, i.e. the elongated bubbles shown in fig. 1, coarsened bubbles around the ion range region m fig. 5, and no bubble accumulation at grain boudaries shown in fig. 6, can be explained by the above reasoning. A thermal desorption spectroscopy of helium implanted into nickel [8] showed that at an implantation fluence of arouna 3 x 102t/m 2, the helium release starts at 1000 to 1100 K. This is in good agreement with the present steady heating experiments, in which bubble coarsening starts at 1073 K. The good correlation between the bubble depth distribution and the ion deposition profile, shown in figs. 5 and 8 suggests that the distrtbution of bubbles
Fig 6 Bubbles in the vtomty of a gram boundary for (a) the pulse and (b) the steady heating cases
1252
T Muroga et al / Heating effects
'~n
He- or D-implanted Nt
Fig 7 Bubbles formed by a pulse heal loading with different power to nickel implanted with 5 keV deutermm ions to 3 x l021/m 2.
formed dunng the pulsed heating should reflect the nascent distribution of the implanted helium or dcutermm. Thus the present pulse heating may be used as a tool to measure the distribution of implanted tons in the specimen.
120
I
I
o
I oo
'
'
30
'
o He =mplontecl • D rmplonted
The present results provide mstght on the effects of a high pulsed heat load on plasma-facing components. Large dimensional changes due to bubble growth are expected when helium or hydrogen isotopes are implanted in plasma-facmg components, where the temperature ts mamtained relatively low, and then pulse heated Grain boundary, degradation may be small, however, in the case of pulse heat Ioadmg because of the small accumulation of bubbles at the gram boundaries.
8o
~ 60
o
o
Heo
,..,~ ~ -
o
.. o
o
o
1
•
;°'°.:''-
~ ca
$$¢" •
"
•
"
-1
~ 2o -
00
,
,
,
,~Ir
~
~"~_IP"
,9
5. Conclusion
I ~II"
50 Depth (nrn)100
i
. •
,
I
Ii
15C
Fig 8 Relation between the depth and the size of bubbles for the case of pulse heatmg m deutenum-implanted nickel compared with those m helium-implanted nickel reproduced from fig 5
Pulse high heat Ioadmg aeter hehum or deuterium implantation can lead to s,..rious bubble coarsemng Large dimensional changf':s are expected m the plasma-facmg surfaces when helium or hydrogen isotopes are implanted and then pulse heated. Grain boundary degradation may be small, however, m the case of pulse heat loadmg because of small accumulation of bubbles at the grain boundaries.
T Muroga et al / Heating effects m He-or D-tmplar, ted Nt
References [1] W. Jaeger and J Roth, J Nucl. Mater 93 & 94 (1980) 756 [2] P.B. Johnson and D J Mazey, J Nuel. Mater, 93 & 94 (1980) 721 [3] K. Niwase, T Ezawa, T Tanabe and F.E FujIta, J Nucl. Mater. 160 (1988) 229 [4] N Yoshlda, N. Ash,zuka, T Fujiwara, T. Kantd and T. Muroga, J Nucl Mater 155-157 (1988) 775 [5] N. Yoshldd, T Kurita, T Fujiwara and T Mnroga, J. Nucl Mater 162-164 (1089)1082. [6] N. Marochov, L J Perryman and P J Goothew, J Nuel Mater. 149 (1987) 296
1253
[7] V N. Chernikov, H Trmkaus, P. Jung and H. Ultmaier, J. Nucl. Maler. 170 (1990) 31. [8] V.F Zelensk,j, I.M Neklyudov, V V. Ruzhitsk,j, V.F. Rybalko, V.I Bendikov and S.M. Kha~an, J Nuci. Mater. 151 (1987) 22 [9] V. Phdipps, E. Vietzke, M. Erdweg and K. Flaskamp, J Nucl. Mater. 145-147 (1987) 292. [10] J G. van der Laan, J. Nucl. Mater. 162-164 (1989) 964. [11] H Kamezdkl, K. Tokunaga, S. Fukuda, N. Yoshida and T. Muroga, J Nucl. Mater. 179-181 (1991) 193. [12] T Muroga, H. Kamezaki, K Tokunaga and N. Yoshida, J Nucl. Mater 176 & 177 (1990) 450.