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Atom-probe field-ion microscope for the study of the interaction of impurity atoms or alloying elements with defects

Conference ·
OSTI ID:7124728

A time-of-flight (TOF) atom-probe field-ion microscope (FIM) designed for the study of defects is described. This atom probe features: (1) a variable magnification internal-image-intensification system; (2) a liquid-helium goniometer stage; (3) a low-energy (less than or equal 3 keV) gas-ion gun for in-situ irradiations; (4) an ultra-high vacuum (approximately 3.10/sup -10/ torr) chamber; (5) a high vacuum (approximately 10/sup -6/ torr) specimen-exchange device; (6) a Chevron ion detector; and (7) an eight-channel digital timer with a +-10 nsec resolution for measuring the TOFs. The entire process of applying the evaporation pulse to the specimen, measuring the voltages, and analyzing the TOF data is controlled by a computer. With this system we can record and analyze 600 TOFmin. Results on unirradiated specimens of molybdenum, tungsten, W/25 at. % Re, Mo/1.0 at. % Ti, Mo/1.0 at. % Ti/0.08 at. % Zr and a special low swelling stainless steel alloy (LS1A) demonstrate the instrument's ability to quantitatively determine concentrations at the 5.10/sup -4/ at fr level and to determine their spatial distribution with a resolution of a few angstroms.

Research Organization:
Cornell Univ., Ithaca, NY (USA)
DOE Contract Number:
EY-76-S-02-3158
OSTI ID:
7124728
Report Number(s):
COO-3158-51; CONF-761027-10
Country of Publication:
United States
Language:
English