A study of electron irradiation damage in single crystals of molybdenum

High-purity zone-refined molybdenum single crystals of the orientations (100),(110),(111) and (112) have been irradiated with electrons of 0.8-1.7 MeV energy at liquid helium temperatures. The lowest energy for atomic displacement was observed for the (100) specimen at Ed = 850 ± 20 keV, which corresponds to a maximum transmitted energy of Td (100) = 36 ± 1 cV. For the other crystals, the apparent thresholds varied betwecn 860 and 890 keV. Near Td, maximum damage rates were obtained for the (100) sample, followed by (110), (111) and (112); at T ≳ 2.5Td , the damage rates were iargest for (110), followed by (111),(100) and (112). Strong anisotropy effects were noted during annealing stage 1 as concerns thc four substages after low aiid high encrgy irradiation for the various orientations.