Materials
Characterization
With one of
the most complete suites of characterization instruments in Canada,
the Materials Characterization Group offers a wide variety of microstructural
characterization services to Canadian companies, universities, and
CANMET-MTL's five research programs. The group also performs core
research on materials characterization methodologies to extend its
own capabilities.
Competencies
range from basic metallography to advanced electron beam and surface
analysis techniques. Specimens are prepared for optical and electron
microscopy, surface analysis and/or quantitative image analysis
from a broad range of materials, including metals, alloys, ceramics,
concrete, composites, coatings, powders and small components. Virtually
all of the characterization equipment is interfaced with a digital
image archival system.
Major
Facilities and Capabilities
- Optical
microscopy: Metallographic specimens are examined in an inverted
optical microscope under bright field, polarized light or Nomarski
contrast illumination at magnifications ranging from 35 to 1000X;
- Image
analysis: Quantitative analysis of optical and electron microscopy
images is performed using a Clemex Vision image analysis system
to determine size, volume fraction and spacing of microstructural
features;
- Scanning
electron microscopy (SEM): The Philips XL-30 SEM has a LaB6
filament and energy-dispersive X-ray spectroscopy (EDS). Secondary
electron (SE) images have excellent depth of field, allowing the
depiction of complex topographical features on fracture surfaces,
powders and polished metallographic cross-sections. The high-quality
back-scattered electron (BSE) images provide atomic number contrast
and, in some cases (depending on the surface finish), crystallographic
contrast. Elemental analysis can be obtained for elements ranging
from carbon to uranium with detection limits down to about 1 wt %;
- Electron
probe microanalysis (EPMA): The Cameca SX50 electron probe
microanalyzer is equipped with four wavelength spectrometers and
EDS. Elemental analysis can be performed from boron to uranium,
with a detection limit from 100% to 10 ppm, depending on the particular
element/matrix combination;
- Analytical
transmission electron microscopy (TEM):
- The
Philips CM20FEG transmission/scanning transmission electron
microscope (TEM/STEM) has 200 kV accelerating voltage, EDS,
and Gatan imaging filter and electron energy loss (EELS) systems.
Chemical information, covering most of the periodic table,
can be obtained from the analysis of excited X-rays (using
EDS) and the energy loss spectra (using EELS) of the transmitted
electrons. Elemental maps and line scans are acquired to characterize
grain boundary and interface segregation and to analyze concentration
gradients. Selected area diffraction (SAD) and convergent
beam electron diffraction (CBED) patterns are used to analyze
the crystal structure for phase determination and to characterize
the orientation relationships between neighbouring grains
and phases;
- TEM
specimen preparation equipment available on-site includes:
dual-jet electro-polishing; precision dimpling; a Gatan Precision
Ion Polishing System (PIPS), which permits argon ion sputtering
at low angles of incidence; and a diamond knife ultramicrotome.
Through a service agreement with a private-sector organization
located at Natural Resources Canada's Booth Street campus
(Fibics Incorporated), CANMET-MTL also has access to the preparation
of TEM cross-sections using focused ion beam techniques;
- Auger
electron spectroscopy/scanning Auger multiprobe (AES/SAM): The
SAM (PHI-600) is a scanning electron microscope combined with
an Auger electron spectrometer. The small electron probe size
(35 nm) and shallow Auger electron escape depth (1-2 nm) allow
for very surface-specific analysis of all elements (except H and
He), with a sensitivity of about 0.5 at.%. Depth profiling can
be performed with a controlled erosion of the surface by argon
ion sputtering to provide both surface and bulk analysis. In-vacuo
sample fracture at temperatures of 23 to -160ºC and subsequent
analysis also may be performed;
- X-ray
photoelectron spectroscopy (XPS): The XPS (PHI-5600) is equipped
with monochromator and non-monochromator dual X-ray sources and
a motorized five-axis specimen stage. Direct, non-destructive
surface chemical composition of all elements (except H and He)
present at the outermost layers of solid surfaces is obtained
from regions as small as 75 microns diameter with <0.1 monolayer
sensitivity (parts per billion). An important feature of XPS is
that it can determine element speciation (chemical forms and oxidation
states). The ion gun permits depth profile studies. The XPS is
also equipped with an ultra-high-vacuum (UHV) -compatible in-situ
reactor and a fracture stage from which the specimen can be transferred
under UHV to the analytical chamber, thereby eliminating an air
exposure (oxidation/contamination) step;
- Access to
additional facilities (focused ion beam [FIB] systems, secondary
ion mass spectrometry [SIMS], variable-pressure SEM [VP-SEM] and
X-ray diffraction [XRD]) is provided through partnerships with
other NRCan divisions and external organizations;
- A complete
metallographic preparation facility is available on-site, including:
abrasive wheel cut-off and low-speed diamond saws; hot mounting
presses and vacuum embedding for cold mounting; automated grinding
and polishing machines; facilities for chemical etching; and programmable
apparatus for electropolishing, electrolytic etching and anodizing.
For further information contact:
Dr. V.Y.
Gertsman
Group Leader
Telephone: (613) 995-2132
Facsimile: (613) 992-8735
E-mail: vgertsman@nrcan.gc.ca
Scientific
Services
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