年報原稿見本(テンプレート)
0.0
Hardness modification in FeCu alloys by using
radiation enhanced segregation
右肩数字：著者代表、連名者の全員に付記
1
2
3
Y. Yamanaka , N. Kawanaka and W. Kaihara
し、脚注所属機関名と対応させること。
When supersaturated alloys are irradiated with high energy particles, point defects are produced and they
enhance the diffusion of supersaturated atoms and their segregation. This phenomenon is called radiation
enhanced segregation. This segregation under irradiation leads to some changes in structures and properties
of alloys. For Fe-based Cu alloys, as Cu-precipitates act as obstacles against the dislocation motion,
energetic particle irradiation causes the increase in hardness of the alloys. The amount of hardness increase
in FeCu alloys depends on irradiation dose, dose rate, irradiation temperature and so on [1,2]. Therefore,
there exist some possibilities of local modification of structures and properties of supersaturated alloys
using the radiation enhanced segregation because the segregation of supersaturated atoms is expected to
occur only in the irradiated region. In this study, we use the swift heavy ion irradiation for the local
modification of hardness in FeCu alloys [3].
A supersaturated alloy, Fe-1.2 wt.% Cu was selected for this experiment. Specimens were
solution-annealed at 850 °C and then were quenched into the water. In this process, Cu atoms were
dissolved supersaturatedly
in the matrix. The specimens were irradiated at 250 °C with 200 MeV Au and
著者／連名者は目次原稿見本と併せるため架空の著者／連名者に変更されていま
Xe ions using a 20
MV tandem accelerator at JAEA-Tokai. During the 。
irradiation, about a half area of each
す。実際は以下の通りでした（ただし右肩の数字は消してある）
specimen was covered
with, F.aHorii,
thick
copper
plate M.
to Kitagawa,
produceR. aOshima,
straight boundary of irradiated and
S. Nakagawa
Y. Chimi,
N. Ishikawa,
unirradiated regions. For some
specimens,
masking
plate
T. Tobita,
R. Taniguchi,
M. Suzuki
and A.with
Iwasea circular hole was put on each specimen
during the irradiation, which restricted the ion-irradiation to the circular region. Changing loads and indents
intervals, Vickers microhardness was measured near the boundary of irradiated and unirradiated regions
after the irradiation. Using the result of some experiments, we determined the suitable conditions for the
two-dimensional mapping of hardness change in the specimens which had been covered with a masking
plate with a circular hole during irradiation.
Figure 1 shows the indent-depth dependence of the change in Vickers microhardness for Fe-1.2 wt.% Cu
specimens irradiated with Xe and Au ions to the fluence of 11013/cm2 at 250 °C. The data for an
unirradiated specimen is also plotted. The Vickers microhardness for unirradiated specimen does not
depend on the indent depth, meaning that the hardness is constant over the observed depth. For the
irradiated specimens, the hardness decreases monotonically with increasing indent depth. This result
indicates that the hardness only near the surface layer about several – several tens m thick increases by the
irradiation. Next, we discuss the hardness change in Xe-irradiated specimens near the boundary of the
work-hardening. Fig. 2 shows the relationship between Vickers microhardness and the measuring positions
for the combination of applied load 50 gf and indentation interval 0.25 mm. For several elements, ionized
1
Japan Atomic Energy Agency (JAEA)
X Y University
3 Z Z Institute
2
with a surface ionization ion source(SIS) and/or a Forced Electron Beam Induced Arc-Discharge (FEBIAD)
type ion source, are shown in Table 1.
220
50gf
Vickerss Hardness(Hv)
Vickers hardness (Hv)
200
180
160
140
120
100
80
160
Au
Xe
Unirradiated
0
5
10
15
20
25
Indent depth (m)
30
35
Fig. 1 Indent-depth dependence of Vickers
microhardness for 200 MeV Xe irradiation
and 200 MeV Au irradiation.
150
140
Unirradiated
Irradiated
130
120
110
1
2
3
4
5
6
7
Position (Interval:0.25mm)
Fig. 2 Vickers microhardness measured
ranging over the irradiated and unirradiated
regions at a regular interval.
Table 1. Release times and fractional rates deduced from the one and/or two exponential fit to the release
data.
Isotope
Ion source
half-life/s
Release time/s
Fractional rate
Literature
94Rb
136mCs
SIS
SIS
2.072
17
1: 1.1
84%
3.2 s[2], 8.2 s[3],
2: 10.7
16%
0.8 s
1: 1.7
30%
2.5 s[2], 21.6 s
2: 22.7
70%
145Ba
SIS
4.3
1: 9
100%
160Eu
SIS
38
1: 12
100%
91Kr
FEBIAD
5.98
1: 3.1
21%
2: 46.9
79%
123gIn
FEBIAD
SIS
39.68
8
10.3 s, 107 s[3]
2.2 s, 3.5 s
1: 7
100%
2.5 s, 8.7 s
1: 1.7@2250℃
100%
6.2 s, 2.3 s, 1.6 s[3]
References
[1] T. Yamada, I. Suzuki and N. Kawakami, J. Nucl. Mater., 123 (2050) 267-270.
[2] T. Yamada et al., J. Nucl. Mater., 456 (2051) 153-160.
[3] N. Kawakami et al., Nucl. Instrum. Methods Phys. Res., B257 (2007) 397-401.