EMP provides advantages over EDS/SEM in steels analysis.
- Detection limits are lower
- elements like Mo (Molybdenum) and S (Sulphur) can be resolved.
Most metals including stainless steels
and aluminium alloys can be characterised quickly and cheaply by electron
microprobe analysis (WDS). All elements present, except for light elements
eg. Carbon and Nitrogen, which are generally not diagnostic, can be
quantitatively determined down to very low detection limits as listed
The inability of the EDS systems to
resolve the Mo and S Peaks is not a problem with the superior
resolution of the WDS crystals. A scraping or small off cut (0.1mm)
is all that is needed - no complex wet chemistry. The difference in
Cr and Ni content as well as the 2%+ Mo in 316 make 304 and 316 easily
technique is very useful in the tracing of metal contaminants in any
manufacturing process to determine source. Inclusions and other impurities
in metal castings can be easily identified.
Full chemical analyses are determined using a fully automated Jeol JXA5A
electron microprobe incorporating computer controlled wavelength dispersive
crystal spectrometers and X-Y-Z stage system, with an accelerating voltage
of 20KV and beam current of 29nA. The beam is defocussed to 15µm for
X-rays are produced in the area excited
by the electron beam, 3 crystals LIF, PET and RAP covering overlapping
ranges of the periodic table are used to focus characteristic X-rays
which are then counted by gas flow counters in each spectrometer. These
counts are compared to X-ray counts from well-characterised natural
and synthetic chemical standards. ZAF (atomic number, absorption, fluorescence)
matrix correction procedures are then used for data reduction.
Sample Preparation Details:
Standard Stainless Analysis
Cr | Mn | Fe | Ni | P | Nb | Mo | S | V | Si
Standard Aluminium Analysis
Al | Si | Ti
Other elements normally at no extra
cost - pls check for element availability.
Basic Operation of an Electron