Dislocation LoopFormation and Growth underIn SituLaser and/orElectron Irradiation
Zhanbing Yang1), Norihito Sakaguchi1), Seiichi Watanabe1*),Masayoshi Kawai2)
Supplementary Figures and Legends 1-5
Supplementary Figure1: Model of equation.
: Reaction volume of vacancy around the V-loop.
: Loop radius.
:Interval betweenlaser pulses (about 0.5 s in the present experiment).
: Vacancy diffusion length during the interval.
Supplementary Figure 2 Models of loop formation under electron beamirradiation, laser irradiation, and simultaneous electron beam and laser irradiation.
FP: Frenkel pair
I: Interstitial
V: Vacancy
SV: Supersaturated vacancy
Supplementary Figure3 cross-sectional view of the laser irradiated (1064 nm, 753 K) specimen
(a)Cross-sectional plane of the specimen cut from the surface to the interior by FIB after laser irradiation.
(b)Higher magnification of part 1 in Fig. S2 (a)
(c)Higher magnification of part 2 in Fig. S2 (a)
Supplementary Figure4Sketch of the loop formation and locations
(a) during laser irradiation and
(b) during thermal annealing.
Supplementary Methods
The material investigated in the present study was SUS316L austenite stainless steel, which is an fcc crystal.Supplementary Table 1 shows the chemical composition of the steel.
Supplementary Table
Supplementary Table 1 Chemical composition of presentSUS316L steel
(mass%)
C / Si / Mn / P / S / Ni / Cr / Mo / V / Al / N0.013 / 0.20 / 1.28 / 0.024 / 0.0010 / 13.32 / 17.24 / 2.04 / 0.04 / 0.014 / 0.0396
Supplementary Discussion
Details of loop formation models under different irradaitions
Based on the experiment results, Fig. S2 depicts models proposedforloop formation under electron beam irradiation, laser irradiation, and simultaneous electron beam and laser irradiation. Under electron beam irradiation, Frenkel pairs (i.e., an interstitial atom and a vacancy) are introduced.Interstitial atoms then easily migrate to form I-loops because of the low migration energy threshold.
On the other hand,during laser irradiation, supersaturated vacancies are created inthe surface region of the specimen(i.e., the melt zone generated by laser irradiation; measured to be 100-150nm)and they then diffuse to the interior of the specimen (heat-affected zone)where theyform V-loops.The analysedcross-sectional view of the surface and interior of the TEMspecimen after laser irradiation (1064 nm, 753 K)prepared by Focused Ion Beam (FIB, JEM 9320) is shown in Fig. S3. During the ensuing thermal annealing, during which supersaturated vacancies were no longer generated, the number of supersaturated vacancies decreased during thermal annealing because of the internal sinks. Figures S4 (a) and (b) show sketches of loop formation and locations during laser irradiation and thermal annealing.
Under simultaneous electronbeam and laser irradiation (which was not performed in the present study), both Frenkel pairs and supersaturated vacancies are considered to be introduced by the simultaneous electron beam and laser irradiation; interstitial atoms then interact with the supersaturated vacancies and also the supersaturated vacancies migrate to form V-loops or other vacancy-type clusters. There is expected tobe competition between the effects of electron beam and laser irradiation.