A transmission electron microscopy study of molybdenum irradiated with helium ions

摘要: Abstract The paper describes the application of transmission electron microscopy to investigate structure developed in surface layers molybdenum samples during irradiations with helium ions range 18 60 keV. Specimen temperatures were varied over a wide from 20° C above 1000°C and both dynamic post-irradiation analytical techniques utilised provide information on separate contributions interstitials, vacancies gas formation damage structures. interstitials formed dislocation loops, subsequent growth network, while combination resulted very high density (≈10 19 cm −3 ) small bubbles temperature (20–700°C). frequently found be aligned body-centred-cubic lattice which produced extra reflections diffraction patterns. Measured [110] bubble spacings between 32 A 50 but showed no significant dependence up 700°C. At doses (≈5 × 10 17 −2 blisters clearly seen, together bubbles, thus indicating rapid rather than slow coalescence bubbles. larger present. insensitivity parameters vacancy mobility, role creating stresses, other aspects, are discussed particularly relation mechanisms blistering. Although definite conclusions reached, it is clear that TEM evidence important any proposed mechanism blister must take this into account.