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Effect of the free surface on void formation in ion bombarded molybdenum

Conference ·
OSTI ID:4844040
Heavy ion bombardment is currently being considered as a technique to simulate neutron damage in CTR components, especially the first wall structure. The use of heavy ion bombardment as a neutron simulation technique has been criticized due to the damage zone being near a free surface (i.e., less than or equal to 1 micron for 5 MeV Ni$sup ++$ ions in molybdenum). The purpose of the present investigation was to examine the microstructure of ion bombarded molybdenum at and below the bombarded surface utilizing transmission electron microscopy to determine the influence of the free surface on void formation. Single crystal molybdenum discs were bombarded at 1000$sup 0$ +- 25$sup 0$C with 5 MeV Ni$sup ++$ ions at surface dose rates of 3 x 10$sup -4$, 1.8 x 10$sup -3$, and 8 x 10$sup -3$ dpa/sec. The void size and density were determined as a function of depth below the bombarded surfaces. Voids were observed within 100 A of the bombarded surfaces and no significant indications of surface-related effects were observed. The variations in void size and density are discussed in terms of the total dose and dose rate at the various regions of examination and the results compared with existing ion bombardment and neutron irradiation data. (auth)
Research Organization:
Battelle Pacific Northwest Labs., Richland, Wash. (USA)
DOE Contract Number:
E(45-1)-1830
NSA Number:
NSA-33-005273
OSTI ID:
4844040
Report Number(s):
BNWL-SA--5398; CONF-751026--28
Country of Publication:
United States
Language:
English