An interpretation of the relief in images of negative replicas is easy when the surface is not strongly 
developed. When there are many different features in the structure a perception of the image of opens 
positive replica is easier because we do not need to do any manipulation on the image in our brain 
(Fig. 3). [solde UT 
or rachber® 
Kurgan 
Das Jona: 
id baths 
schied 2 
T0500 
sehr untef 
di 3 ptt Abstract 
Fig. 3: Comparison of images of negative (left image) and positive (right image) replicas of a by differ 
microstructure of a 16Mo3 steel specimen. Images taken with the sector-shaped ring BSE detector. lavers ag 
Beam energy Eq = 20 keV. Images taken at different locations. boul 
if. 
Discussion and conclusions. 
Metallographic replicas can be observed in the SEM with the use of SE and BSE signals and 
different BSE detectors can be used. BSE images obtained with a high take-off BSE detector have 1. Einfüh 
poor resolution and do not give a proper impression of topography. Detectors of this type, e.g. Das glen 
semiconductor annular-split top detectors, are not recommended for such observations. The SE aus Werk 
signal is sensitive to a surface inclination only at large inclination angles, so SE images appear Hilfe der 
relatively flat with bright dots at small features protruding from the surface and bright lines at the Jösen. Ein 
edges of larger surface features (edge effect). Small holes can disappear in images, moreover the SE stoff: bzw 
signal is very sensitive to any contamination of the specimen surface. Optimum representation of Arbeit zu 
the replica relief we can obtain with the use of low take-off BSE. We can detect such electrons with Beispiele 
the standard detector of SE in a conversion mode of BSE detection but more reproducible signal we unlegierte 
can obtain with the sector-shaped ring scintillation detector optimized for detection of topographic dungen z 
contrast. Negative and positive replicas can be observed — a preparation of negative replicas is Komose 
simpler but positive replicas give a direct and unambiguous representation of topography. Contrast 
of small features at typical beam energies 15 — 30 keV is small because of relatively large 2. Versu 
interaction volume of electrons in the specimen. This interaction volume can be decreased and the Die Aur 
contrast improved by lowering the beam energy. Detection of BSE is less efficient at low energies durchge 
but this problem can be solved e.g. by acceleration of BSE in front of the detector (9). strahlwir 
zu einen 
References: strahlwm 
(1) B. Neubauer, F. Arens-Fischer: VGB Kraftwerkstechnik 63 (1983), 637. werden 
(2) A. Hernas, J. Dobrzanski: “IX Conference on Electron Microscopy of Solids”, Kraköw- Abschlie 
Zakopane, Poland (1996), 621. Komgrei 
(3) T.E. Everhart, R.F.M. Thomley: J. Sci. Instr. 37 (1960), 246. von der | 
(4) S.H. Moll, F. Healey, B. Sullivan, W. Johnson: Scan. Electr. Microsc. 1978, Pt I, 303. Different 
(5) A. Boyde, M.J. Cowham: Scan. Electr. Microsc. 1980, Pt I, 227. Strukture 
(6) A.B. Munden, D.E.Y. Walker: J. Phys. E 6 (1973), 916. 
(7) O.C. Wells, C.G. Bremer: Rev. Sci. Instrum. 41 (1970), 1034 Ak Noch 
(8) J. Hejna: Scan. Microsc. 8 (1994), 143. ro 
(9) J. Hejna: Scanning 17 (1995), 387. «fa 
ach 
350