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Radiation enhanced diffusion of Ni(63) atoms in single crystals of nickel having a <100> orientation was investigated in the temperature range between -100 and +800 C using 1.85 MeV electrons. Between -100 and +100 C a very small, almost temperature-independent, radiation-enhanced diffusion coefficient of the order of 5 x 1.0 E-19 cm2/s was obtained. The diffusion coefficient due to dynamic crowdions is D(dyn) = 0.5.a(2).K.N and for the number of replacement collision sequences approximately N = 2.5 x 1.0 E5 is obtained. This number is about a factor of five larger than that obtained from measurements of the radiation damage rate for copper and gold. Radiation-enhanced self-diffusion above 100 C is determined by an interstitial diffusion mechanism. The migration activation energy of interstitials is 1.03 eV, decreasing with increasing high energy particle flux. In the next-nearest surface region, radiation-enhanced diffusion is determined by a vacancy diffusion mechanism and the migration activation energy of vacancies is 1.45 eV decreasing with increasing high energy particle flux. By irradiation with 1.85 MeV electrons the Ni(63) atoms were 900 Angstrom displaced by channelling, if they were partly oxidised, putting them on the surface of the crystal prior to irradiation.

Additional information

Authors: SCHÜLE W, JRC Ispra (IT)
Bibliographic Reference: Paper presented: Frühjahrstagung der Deutschen Physikalischen, Berlin (DE), March 19-24, 1995
Availability: Available from (1) as Paper EN 38929 ORA
Record Number: 199510663 / Last updated on: 1995-07-07
Original language: en
Available languages: en
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