212 Prakt. Met. Sonderband 38 (2006) 
When analysing the precipitate volume fractions, the amount of M23Cs precipitates stays 
moreless constant from the heat treated sample to the longest running thermally aged and 
creep loaded conditions (Figure 4). In contrary, the volume fraction of VN is clearly As 
decreasing after 16.000h in both, thermally aged and creep loaded samples (Figure 5). (cc 
This is clearly a result of the decreasing number density. pro 
Analysing the evolution of the M23Cs mean diameters, this parameter increases for sar 
thermally aged and creep loaded samples (Figure 6). Additionally considering the constant — U 
volume fraction and decreasing number density, these precipitates clearly show the effect the 
of coarsening. mo 
In contrary, the VN moreless keep their initial size (Figure 7), except for a slight tendency pre 
in the thermally aged sample to grow. (by 
cor 
3.10° wa x 
+ «— heat treated ——therm. aged 1.6.10" Wa aESd at t 
= 2.10° -=- creep loaded = Seep 10806 Thi 
N = 3 L200 fas 
g 210° stu 
8 „as receivi 8.17 phe 
5 1.10° Ma 
£ ; a 
3 5.10% = 4" nes tre adc 
a 5000 10000 15000 20000 0 5000 10000 15000 20000 
t/h . skin - 5. 
Fig. 2: Number density of M23Cg prec. Fig. 3: Number density of VN precipitates 
4 0.35 q The 
——therm. age age 
A 
. 0.30 =- creep loaded CB 
“| heat treated 0.25 
30 ; : : as received oft 
25 u / 10.20 \ the 
5 2.0 li 2 0.15 / San 
E 1.3 as received 5 010 . mo 
7 1.0 aly 4 . rea 
05 SE 0.05 heat treate. res 
; -=- creep loaded 
00 a} . 0.00 : - He For 
0 5000 10000 15000 20000 0 5000 10000 15000 20000 7 
t/h t/h &P 
Fig. 4: Volume fraction of M23Ce phase Fig. 5: Volume fraction of VN phase inve 
tof 
170 90 
——therm. aged 
160 
150 80 +- creep loaded 
AC 
140 = 70 
£ 
= 130 S 
a — | 
A 120 a0 on 
110 50 
100 A as received ——therm. aged 40 a 
90 1 heat treated -=- creep loaded heat treatea RE 
80 x - r - 30 
0 5000 10000 15000 20000 0 5000 10000 15000 20000 
t/h t/h 
Fig. 6: Mean diameter of M23Ce prec Fig. 7: Mean diameter of VN precipitates [1] 
SF