Effects of pulsed dual-ion irradiation on phase transformations and microstructure in Ti-modified austenitic alloy Page: 4 of 28
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3
2. EXPERIMENTAL DETAILS
The approximate composition (wt %) of the Ti-modified austenitic
stainless steel used in this study was Fe-15Cr-15Ni-2Mc-2Mn-lSi-0.2Ti-
0.05C. Solution-annealed (1373 K) specimen disks 3-mm-diam by
0.35-mm-thick were irradiated at 950 K in the ORNI, dual-ion beam Van de
Graaff facility. As in the previous pulsing experiments at this facility
[7,8] the instantaneous dose rate was maintained at a low level of ~3 x
_ 3
10 dpa/s in the peak damage region in order to limit temperature
variations caused by beam heating to <4 K as measured with an infrared
Si'-
pyrometer. Doses from 1 to 70 dpa were attained in this experiment (some
prior unpulsed data to 125 dpa is also compared). Bombardments employed
either 4 MeV ^Ni+"^ ions alone or simultaneous injection of 4 MeV
and 0.2—0.4 MeV He+ at a ratio of 20 appm He/dpa throughout the central
damage region. Synchronized interruption (pulsing) of both beam lines was
accomplished with solenoid-actuated beam stops; the periods used are
designated "slow pulse" (60 s on/off), "fast pulse" (Is on/off) and con-
tinuous bombardment as a control.* Details of the bombardment facility
and procedures have been given elsewhere [12].
Following ion bombardment, specimens were electrocheraically thinned;
first, from the bombarded side to a depth of 0.6 pm, and then from the
back side to perforation. Following transmission electron microscopy
(TEM) examination, carbon-film replicas were made from some foils to cap-
ture precipitate particles for analytical electron microscopy (AF.M). A
JEM 120CX instrument operated at 120 kV was used for both TEM and AEM.
*Just as charged-particle irradiation permits the simulation of years
of reactor damage by hours of bombardment, so too should the pulsing
periods be shortened from possible "burn times" of hours to the much
briefer periods employed here.
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Lee, E. H.; Packan, N. H. & Mansur, L. K. Effects of pulsed dual-ion irradiation on phase transformations and microstructure in Ti-modified austenitic alloy, article, January 5, 1983; Tennessee. (https://digital.library.unt.edu/ark:/67531/metadc1093654/m1/4/: accessed April 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.