Analysis and Identification of carbides with AFM and TEM 
SS in tannı 
al nn After electropolishing small particles are visible in the AFM images in ferritic grains. Fig. 2 shows 
Oper, The a linescan through such particles and an area with pearlite. The height-profile along the linescan 
tte rang fee shows similar height differences between cementite and ferrite as between the particles and ferrite. 
in indentine Both phases are etched similarly in the electropolishing process, which indicates that both phases 
by Oliver om may have a similar structure and constitution. Therefore, these particles were assumed to be 
 Calibrated ir carbides. Nevertheless, to prove that the particles visible in ferrite are carbides an elemental analysis 
alsin ah has to be performed. Since the particles are very small with a size of only less than 50nm TEM 
inl investigations were used for a chemical analysis. 
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Fig. 2: AFM image of the microstructure with pearlite and ferrite. Inside the ferritic grains small 
carbides are visible. The linescan through the AFM image shows the height profile, from which it 
can be deduced that carbides and cementite lamellae show the same height after preparation. 
TEM replicas were used to identify the particles imaged with the AFM and to determine the 
chemical composition of carbides inside ferritic grains with an EDS system. TEM elemental 
mapping images shows carbides with a similar size than that found in the AFM images. EDS 
spectra from such particles show a clear enrichment of Vanadium inside the particles. Therefore it 
could be verified that the particles imaged with the AFM inside ferrite are carbides. 
Mechanical properties of ferrite and pearlite studied by nanoindentations 
With nanoindentations the hardness of ferrite and cementite was measured in pearlite with a lamella 
distance of less than 100 nm and in comparison also in ferrite. Fig. 3 shows an AFM image from 
pearlite, where small indents (black) are visible in cementite and between cementite lamella. The 
hardness and Young’s modulus were determined from the load-displacement curves of these 
indentations. 
The hardness of ferrite at 0.1 mN and 0.2 mN load is considerably lower than that of pearlite. 
Cementite and ferrite lamella inside pearlitic grains show only small hardness differences. Since the 
size of the indents is close to the lamella spacing the high hardness of ferritic lamella inside pearlite 
can partly explained by an influence on the measurements from cementite and has to be analyzed 
more carefully. The hardness at this load level is higher than at larger indentation depths which is 
yea Show understood as an indentation size effect [5]. The modulus measured by the nanoindentations were 
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