Computer-controlled time-of-flight atom-probe field-ion microscope for the study of defects in metals

Technical Report · Sun Aug 01 04:00:00 EDT 1976

DOI:https://doi.org/10.2172/7234261· OSTI ID:7234261

Hall, T M; Wagner, A; Seidman, D N

A time-of-flight (TOF) atom-probe field-ion microscope (FIM) specifically designed for the study of defects in metals is described. This atom probe features: (1) a variable magnification internal-image-intensification system based on a channel electron multiplier array (CEMA) for viewing the FIM image; (2) a liquid-helium-cooled goniometer stage which allows the specimen to be maintained at a temperature anywhere in the range of 13 to 450 K; (3) a low energy (less than or equal to 3 keV) gas ion gun for in-situ irradiations; (4) an ultra-high vacuum (approximately 3 . 10/sup -10/ Torr) chamber to minimize specimen contamination; (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 +- 10 nsec resolution for measuring the TOFs of the pulse-field evaporated ions. The entire process of applying the evaporation pulse to the specimen, measuring the dc and pulse voltages, and analyzing the TOF data is controlled by a Nova 1220 computer. Data in the form of a histogram of the number of events versus the mass-to-charge ratio is displayed on a Tektronix graphics terminal. An extensive set of computer programs to test and operate the atom-probe FIM have also been developed. With this automated system we can presently record and analyze 600 TOF min/sup -1/. The instrument can clearly resolve the seven isotopes of molybdenum and the five isotopes of tungsten. Investigations of alloys have shown that the concentration of rhenium in a W-25 at. percent Re alloy; and the concentrations of titanium and zirconium in a Mo-1.0 at. percent Ti alloy and a Mo-1.0 at. percent Ti-0.08 at. percent Zr alloy can be easily measured. Investigations of a low swelling stainless steel alloy (LS1A) and a metallic glass alloy (Metglas 2826) have shown that all constituents present at a level of 0.05 at. percent or higher can be readily determined.

• Research Organization: Cornell Univ., Ithaca, NY (USA)
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• DOE Contract Number: EY-76-S-02-3158
• OSTI ID: 7234261
• Report Number(s): COO-3158-50
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400100 -- Analytical & Separations Chemistry
440300* -- Miscellaneous Instruments-- (-1989)
47 OTHER INSTRUMENTATION
AUTOMATION
CHEMICAL ANALYSIS
CONTROL EQUIPMENT
CRYOSTATS
DEFECTS
DESIGN
ELECTRON MULTIPLIERS
ELECTRON TUBES
ELEMENTS
EQUIPMENT
GONIOMETERS
ION MICROPROBE ANALYSIS
ION MICROSCOPES
MEASURING INSTRUMENTS
METALS
MICROCHANNEL ELECTRON MULTIPLIERS
MICROSCOPES
NONDESTRUCTIVE ANALYSIS
THERMOSTATS
ULTRAHIGH VACUUM
VACUUM SYSTEMS