The Projectile Mass Dependence of the Amorphization Process and the Critical Temperature in the Ion Irradiated CuTi
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THE PROJECTILE MASS DEPENDENCE OF THE AMORPHIZATION THE CRITICAL TEMPERATURE IN THE ION IRRADIATED CuTi J.
KOIKE*,
P.
R. OKAMOTO**,
PROCESS AND
M. MESHII*
* Department of Materials Science and Engineering,Northwestern University, Evanston,IL. 60208 ** Materials Science Division, Argonne National Laboratory, Argonne, IL.60439 ABSTRACT CuTi was irradiated with 1MeV Ne+ and Kr+ at various temperatures in the Argonne-HVEM interfaced to a tandem accelerator. The integrated intensity of diffuse ring was measured by a microdensitometer and analyzed by Gibbons model for the dose dependence of the amorphous volume. The results indicate that the direct amorphization occurs in a single damage zone with Kr+, but the overlapping of three damage zones is necessary with Ne+. The critical temperature for amorphization was 401±22K for Ne+ and 543±20K for Kr+, respectively. With Kr+ , the critical temperature was nearly equal to the thermal crystallization temperature of an amorphous zone embedded in the crystalline matrix. Using the present observations, the relation between the amorphization process and the critical temperature is discussed. INTRODUCTION In recent years, it has been observed that glass formation by solid-state amorphization can occur in many ways. Among them, radiation induced amorphization is of interest in studying the transition process. In the case of heavy ion radiation, considerably denser damage, compared to electron or lighter ion radiation, is produced along the projectile path. The damage structure depends on the mass and the energy of incident ion as well as the radiation temperature. The amorphization process is also influenced by these parameters. Amorphization of Si has been extensively studied from this viewpoint [1-4]. Theories based on the various amorphization processes have been developed to explain the temperature and dose dependenc-e of amorphization [5-7]. Similar amorphization processes have been reported for irradiated intermetallic compounds (8-13]; however, the temperature and mass effects on amorphization have not been well established in relation to the damage structure. In the present work, we studied the amorphization process and the critical temperature for amorphization, as a function of the ion mass. The amorphization process in CuTi irradiated by 1MeV Ne+ and Kr+ has been analysed using Gibbons' model (6] and discussed with damage parameters. Furthermore, the critical temperature is discussed with respect to the amorphization process. EXPERIMENTAL The nominal Cu-54at%Ti alloy button was melted by arc-furnace and subsequently annealed at 850K for a week. TEM
Mat. Res. Soc. Symp. Proc. Vol. 100. ©1988 Materials Research Society
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samples were spark cut and prepared by jet polishing. The resultant sample contained two phases: CuTi and CuTi 2 . CuTi was irradiated with IMeV Ne+ and Kr+ ions with a flux of 3.4xl0 1 1 ions/cm2 .s at temperatures from 292K to 563K. The radiation induced structural changes were monitored continuously in the Argonne-HVEM interfaced to a tandem a
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