Prakt. Met. Sonderband 41 (2009) 315 
of the external T_T 
cq - p(t 
yxidation zone Ex) =r, —r(t)=71, a (D 
of the internal PO). Proz Po. 
e during high- 
os the increase where ry is the outer radius of the sample and (2) the radius of the unoxidized part of the sample. 
ample. On the Finally, the electrical resistance values from point A to B in Fig. la were transformed using the eq. 
e solute atoms 1 into the parameter Er(2), showing the penetration of the IOZ into the alloy - the kinetics of internal 
s evident, that oxidation of Ag-Sn (2 at.% Sn). These results were compared with calculated kinetics according to 
~reases almost Wagner’s theory [15] and kinetics determined by metallographic analysis of partially internally 
naller as in the oxidized samples. The comparison of internal oxidation kinetics obtained by all used methods is 
jue to internal shown in Fig. 3 and gives good correlation with the same trend of IOZ growth (Fig. 3). In these 
1 resistance of diagram, the square of & normalized with the square of ry is shown on the y axis and the ¢ 
of the sample. normalized with zo on the x axis. The 7, represents the theoretical time needed for the internal 
| limits. due to oxidation of the sample according to Wagner’s theory of oxidation. 
; 1,0 I 
—— Electrical resistance measurements 
09 3 = = = Wagner's theory 
! Metaliographic analysis 
08 | 
07 
0,6 
Z 05 
Bp i 
04: 
0,3 + 
0,2 + 
m. TE —— 0 x 
200 um ! 
0,0 Bent LA LM be be La 
00 01 02 03 04 05 06 07 08 08 10 11 12 
y at T=800°C and 
y t/t 
Fig. 3: Comparison of kinetics of internal oxidation of Ag-Sn (2 at.% Sn) alloy at T=800°C determined by different 
methods 
yeriments were 4 Conclusions 
sh this we have 
microstructure In this paper the measurement method enabling in-situ measurements of electrical resistance on the 
stance of such basis of the four-probe method during annealing of metallic materials in oxidizing atmosphere was 
Measuring the described. The use of this new measurement method for in-situ monitoring and characterization of 
1d knowing the high-temperature oxidation presents a strong tool that will contribute to a better fundamental 
d alloy po, the understanding of the phenomena that occur during high-temperature oxidation of metallic materials. 
The novel method enables non-destructive sensing of fundamental features during high-temperature 
oxidation of metallic materials. As for instance, it can distinguish between growth of the external