Serbian Society for Microscopy
Academy of Medical Sciences, SMS
ELECTRON MICROSCOPY IN MATERIAL SCIENCE AND
ENGINEERING AT UNIVERSITY OF NOVI SAD
Leposava Šidjanin1
1. BACKGROUND
The laboratory for electron
microscopy in Novi Sad was
established in 1978, twelve years after
the first electron microscope have
been used in Serbia. At that time, two
JEOL electron microscopes have been
installed as a result of enthusiastic
initiative by young scientists from
Faculty of Technology, Faculty of
Science, Faculty of Medicine and
Faculty of Technical Sciences and
sincere support of Academic Paula
Putanov. The first two electron
Fig. 1. Scanning electron microscope
microscopes include scanning electron
JEOL JSM-35
microscope (SEM) JEOL type JSM35 equipped with Wavelength Dispersive X-ray
Spectroscopy (WDX) (Fig. 1) and transmission
electronic microscope (TEM) JEOL type
JEM-100C operating at 100kV (Fig. 2). In 2002,
a new fully computerized JEOL scanning
electron microscope type JSM-6460 LV
equipped with Energy Dispersive X-ray
Spectroscopy (EDX) (Fig. 3) was obtained.
At the same time, the laboratory for
electron microscopy has changed its name into:
The University Center for Electron
Microscopy (UCEM) in Novi Sad.
Scientists from the areas of biological,
biomedical and materials sciences from Novi
Sad and entire Serbia have used and gained
benefits from electron microscopes at the
UCEM. However, in this paper, some results
from the area of materials science and
1
Fig. 2. Transmission electron
microscope JEOL JEM-100C,
operating at 100kV
Faculty of Technical Sciences, University of Novi Sad, Trg. Dositeja Obradovića 6, Novi Sad
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Serbian Society for Microscopy
Academy of Medical Sciences, SMS
Fig. 3. Scanning electron microscope JEOL JSM-6460LV
engineering, such as these shown in Fig. 4, generated by the scientists from the
University of Novi Sad, will be presented.
b)
a)
Fig. 4. SEM micrographs of brittle and ductile fracture in carbon steel (0.4% C): [1]
a) with pearlite-ferrite normalized microstructure showing the change in cleavage plane at a
subgrain boundary and characteristic river pattern
b) with a quenched and tempered martensite microstructure, showing large dimples associated
with oxide inclusions and small dimples associate with small carbide precipitates.
In Figures 4a,b characteristic morphology of brittle (Fig. 4a) and ductile (Fig.
4b) fracture patterns typically found in carbon steel with 0.4% of carbon are shown.
These figures were also used with permission as good examples in textbook titled”.
The Modern Physical Metallurgy”-1985, [1].
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Serbian Society for Microscopy
Academy of Medical Sciences, SMS
2. MATERIALS RESEARCH
During the 70s, metal industry was vital for the development of the region and
therefore strongly influencing research activities at the Faculty of Technical Sciences,
Institute for Production Engineering. It was not surprising that R&D (research&
development) activities were primarily directed toward the development of new and
improvement of existing metallic materials particularly those processed using
machining, metal forming and casting technologies. Until 2000, materials of the
primarily concern were iron base and aluminum alloys including high value ferritemartensite steels, microalloyed high strength steels for welding, cast irons in as-cast
and austempered condition and high strength aluminum alloys. Other research
activities include plasma-nitriding and physical vapor deposition (PVD) surface
technologies, fracture mechanic methods for examination of welded joints and “quick
stop” method for chip formation during machining which is rapid enough to freeze the
cutting action.
After 2000, the research activities have been expanded in the areas of structural
ceramic materials and advanced glasses in collaboration with Faculty of Technology
and Institute of Physics, respectively.
Electron microscopy has been used in support of most of the mentioned research
activities for which the results have been presented and published in international and
domestic journals and conferences [2-16].
Selected results shown in Figures 5-13 are part of those researches
b)
a)
Fig. 5. TEM micrographs of a specimens of Al-5Zn-2Mg alloy
after precipitation-hardening [2,3] a) bright field for continuous heat treatment, with
V5=0.06°C/min: diffraction pattern for [011] orientation, where arrow at spot diffraction
indicated dark field image used along 200; it was obtained: extinction distance ξg= 67.3 nm,
foil thickness 100.95 nm and precipitation density Nv=2.32X1017 (GP zone/cm3).
b) bright field for duplex (multiple) ageing treatment at 190°C/70 min,
(precipitate free low angle grain boundary zone W = 125 nm)
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Serbian Society for Microscopy
Academy of Medical Sciences, SMS
Diffraction pattern
Bright field image
Dark field image along 002γ
Fig. 6. TEM micrographs of dislocated lath martensite in dual phase steel which is required
for cold forming into the wire of type cord of diameter 0.25 mm. Initial rods 5.5 mm in
diameter were drawn by 14 passes with no intermediate annealing;
samples of type cord drown have exceeded strengths of 2700 MPa with 2 % tensile
elongation; diffraction pattern consist three zones:
<100>αm || <110>γ || <111>αm [4,5]
b)
a)
Fig. 7. SEM micrographs of ferrite-martensite dual phase steel [5,6]
a) decohesion and void formation at martensite/ferrite interface during wire drawing from
rod Ø 5.5 mm in diameter to the wire with true strain of ϕ =1.20,
b) crack growth along ferrite/martensite interface, through ferrite grains and through coarse
martensite in 8 mm hot rolled strip, with low rate crack propagation (∆K=∆Kth)
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Serbian Society for Microscopy
Academy of Medical Sciences, SMS
10 µm
30 µm
b)
a)
Fig. 8. SEM micrographs of fracture mode in pearlitic ductile iron grade SG 600 after one step
and multistep fatigue tests under axial bending condition which were carried out
on segments taken from two series of machined crankshaft castings
in order to determinate the fatigue life and fatigue limit [7]
a) fatigue fracture region indicate fatigue cracks spread in wavelike or zigzag paths, forming
“hills and valleys” with shearing surface of fracture
b) fast fracture region indicate brittle transcrystalline and planar fracture
b)
a)
Fig. 9. SEM micrographs of chip patterns obtained using quick-stop method which is rapid
enough to freeze the cutting action [8, 9] a) chip pattern of carbon steel Č1730; (normalized
microstructure; cutting speed 41m min−1 ,0,742 mm/rev feed, cutting depth 1,5 mm) b) chip
pattern of Ti3SiC2 (cutting speed 56 m min−1 ,0,442 mm/rev feed, cutting depth 4,4 mm)
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Serbian Society for Microscopy
Academy of Medical Sciences, SMS
Fig. 10. Microchemical analysis of Si and S
of nonmetallic inclusion in steel
using WDX [10]
Fig. 11. SEM micrograph of brittle fracture
of (As2Se3) 100- x (SbSI)x glasses
with x=70 at.% [11 ]
a)
b)
Fig. 12. SEM micrograph of thin coatings on steel [12, 13] a) fracture morphology of TiN
(PVD) coating cross-section, (columnar structure - according to zone model of Thornton);
b) adhesion test of pn/TiN (PVD) coating by scratching, (cohesive failure and the
delimitation of the coating)
Bright field image
Diffraction pattern
and scheme
Dark field image along 002γ
Fig. 13. TEM micrographs of ADI microstructure known as ausferrite, which consists
ausferritic ferrite free of carbide and stable with high carbon enriched, reacted
retained austenite [14, 15]
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Serbian Society for Microscopy
Academy of Medical Sciences, SMS
b)
a)
Fig. 14. SEM micrographs of ADI material alloyed with 0,45% Cu showing influence of the
volume fraction of reacted retained austenite on fracture mode [16]
a) brittle fracture in specimen austempered at 400°C for 4h,
(the volume fraction of reacted retained austenite is zero);
b) ductile fracture in specimen austempered at 350°C for 2h,
(the microstructure of ausferrite contained 20% reacted retained austenite);
Scientists from Faculty of Technology, University of Novi Sad, Department of
Materials Engineering and Department of Basic Engineering Disciplines, are the
groups who also use the electron microscopy as a necessary method for materials
characterization. Their research activities are correlated mostly to traditional ceramic,
advanced ceramic and catalysts.
The researches in the area of traditional ceramics led by Prof. dr. J. Ranogajec
were very important for province of Vojvodina. Through those research programs
Vojvodina became the regional leader in manufacturing of ceramic tiles and bricks.
The SEM facilities were used either in the field of science or for quality control and
characterization of powder materials necessary for production of bricks and tiles. The
powder materials were characterized using SEM at two levels, small magnification
(<500×) for identifying morphology and size of individual particles and larger
magnification (>1000×) for characterization of agglomerated structures. The SEM has
been also used for quality control of tiles before final firing in order to evaluate
homogeneity and density and after firing and freezing/thawing procedure to check
crystallinity and porosity of the products (Fig. 15), [17, 18].
The new trends in advanced ceramics include research programs related to
synthesis of nano powders, novel forming and heat treatment methods, and also
deposition of thin layers on different substrates (Fig. 16 and 17) [19, 20].
Research activities in the area of catalyst include synthesis, physical-chemical
characterization, the testing of activity, selectivity and working duration of catalyst
(Fig. 18), [21].
For all ceramics research programs, electron microscopy facilities were also
necessary.
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Serbian Society for Microscopy
Academy of Medical Sciences, SMS
a)
b)
c)
d)
Fig. 15. SEM micrographs of traditional ceramics [17,18]:
a) the cross section of the floor tiles,
b) micropore as potential structure defect in ceramic material
c) carbonate phase CaO (labeled with C) in ilit/carbonate system sample fired at 1050°C
before freezing/thawing procedure
d) needle-like crystal of zeolite (labeled with Z) and calcium silicate hydrates(labeled with
CSH) in ilit/carbonate system sample fired 960°C after freezing/thawing procedure
a)
b)
Fig. 16. SEM micrographs of Al2O3 ceramic material obtained using “freeze-casting
”technique with different pores size [19]
a) macropores in size of 50-200 µm
b) spherical Al2O3 particles and interparticles mesopores in size of 50 nm;
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Serbian Society for Microscopy
Academy of Medical Sciences, SMS
a)
b)
Fig. 17. SEM and HRSEM micrographs of titania coatings with uniform thickness
less than 1 µm obtained by sol–gel method after heat treatment at 560°C, for 7 h
on different substrates (C: coating, S: substrate)
a) titania coating on single crystal quartz with (101) orientation and grain size of 17nm,
b) titania coating on single crystal silicon with (100) orientation and grain size of 27nm,
a)
b)
Fig. 18. SEM micrographs of morphology of NiO-Al2O3 catalyst [21]
a) heat treated at 400oC; b) heat treated at 700oC
3. REFERENCES
[1]
[2]
[3]
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&Co Publisher, Ltd, 1985) 489 (autor fotografija L.Šidjanin)
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Avramovic-Cingara G., Rogulic M. and Mihajlovic A., A study of grain
boundary precipitate free zone formation in an Al-Zn-Mg alloy by continuous
heat treatment, 8th International Light Metals Congress, Leoben-Vienna, (1987)
435-440
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Serbian Society for Microscopy
[4]
[5]
[6]
[7]
[8]
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[10]
[11]
[12]
[13]
[14]
[15]
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[18]
[19]
[20]
[21]
Academy of Medical Sciences, SMS
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