obtained at extremely low loads where tip shape effects have a big influence on the results. Anton 
Probably this caused the modulus data from the ferrite grains to be lower than expected. Although 
the absolute values of hardness and modulus measured at a load of 0.1 mN and 0.2 mN are different Jorg 1 
from the values measured with standard tests, differences in the mechanical properties can be 
detected reliably also at a load level of 0.1 mN. [ren 
16 - 220 mr 
2.00 = 14 ferrite grain peariite la plize frie rain - pros © bb 
5 o Jo © 9 Bild 
= 12 o o* oY aaa © — 160 go ; 
8 10] ° “be 140 3 
10 {° 5 o looaa® aoe a PCO nn 3 
AEE Cm 
0 TT ~~. °° 100 
6 a Aah, to 1 80 
Ady BTA TL AL a aa cementite | ferrite 
4 44 A 0.1 mN lo mN 60 
o modulus 40 
2 4 Hardness 20 
’ 7 — - J 
' "a 2.00 0 5 10 15 20 25 30 35 40 45 50 
indent no. 
Fig.4: Hardness and modulus of pearlite and ferrite. The AFM image on the left shows impressions 
left from small nanoindentations in pearlite. 
Conclusions i 
” 
The microstructure of different alloys was analyzed by comparing AFM and TEM images. The Hr 
combination of both microscopic techniques allows reliable characterizations of small 
microstructures. The TEM was used to identify the chemical composition of carbides, which were 
found in the AFM images. With nanoindentations the different mechanical properties of ferrite and 
cementite were determined. In ongoing work the influence of small carbides on the global 
mechanical properties of microalloyed steels is investigated. 
Acknowledgement 
Financial support from the DFG Graduiertenkolleg “Neue Hochleistungswerkstoffe fiir effiziente 
Energienutzung” is acknowledged. 
References: 
[1] M. Géken and H. Vehoff, Scripta Materialia 35, 983-989 (1996) 
[2] K. Durst, M. Goken, to be published 
[3] W.C.Oliver, G.M.Phar, J. Mater. Res., Vol. 7/6, pp. 1564-1583 (1992). 
[4] M. Goken, M. Kempf, M. Bordenet and H. Vehoff, Surf. Interface Anal. 27, 302 (1999) 
[51 W.D. Nix and H. Gao, J. Mech. Phys. Solids 46 (1998) 411. 
94