Effects of electron irradiation on precipitation in Al-3.5% Cu

Journal Article · Sat Nov 01 04:00:00 EST 1975 · Acta Metallurgica

DOI:https://doi.org/10.1016/0001-6160(75)90137-6· OSTI ID:4058841

Sklad, P. S.; Mitchell, T. E.

The effects of electron irradiation on precipitation in Al--3.5 percent Cu was studied in the temperature range 20--200⁰C by high voltage electron microscopy. G. P. zones gradually disappear during irradiation and are replaced by theta' precipitates. The intermediate stage of theta'' precipitation is inhibited by irradiation. If theta'' precipitates are introduced by preaging, they are also gradually replaced by theta' precipitates during irradiation, even in the temperature range where they would normally grow. The growth of theta' precipitates is observed to be enhanced at all temperatures between 20 and 200⁰C (above 200⁰C the growth rate is normal), especially at the lower temperatures. In fact, the growth rate is approximately constant between 20 and 120⁰C where essentially no growth is observed under normal aging. These results are explained in terms of a model of enhanced diffusion resulting from the annihilation at fixed sinks of the vacancies and interstitials created by irradiation; the fixed sinks are the precipitates themselves. The irradiating conditions in the microscope are shown to give rise to a constant contribution to the diffusion coefficient, D_rad approximately equal to 2 x 10^-16 cm² s for the temperature range 20--120⁰C. Irradiation also gives rise to small dislocation loops in either the quenched or the aged condition, but these are only observed at room temperature. Voids are never observed; apparently, the precipitates act as sinks for both the vacancies and interstitials.

• Research Organization: Case Western Reserve Univ., Cleveland
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-023816
• OSTI ID: 4058841
• Journal Information: Acta Metallurgica, Journal Name: Acta Metallurgica Journal Issue: 11 Vol. 23; ISSN 0001-6160
• Country of Publication: United States
• Language: English

Related Subjects

*ALUMINIUM BASE ALLOYS-- PHYSICAL RADIATION EFFECTS
*COPPER ALLOYS-- PHYSICAL RADIATION EFFECTS
36 MATERIALS SCIENCE
DIFFUSION
DISLOCATIONS
ELECTRON BEAMS
GUINIER- PRESTON ZONES
INTERSTITIALS
PRECIPITATION
VACANCIES