Prakt. Met. Sonderband 30 (1999) 341 
100 - 
Ral 
“gr 80 | —e— 900°C 
~—a— 1050°C 
I nl | —y— 1150°C 
5 
> 40 
- A = 
a 20 A 
0 oe rrr error] 
‚0 4 100 1000 
Time, min 
Fig.3: Percent transformed ferrite as a function of annealing time. 
— Wr 
nn 100% 
100% ; . 
80% 
80% 
p 60% »0 | 60% Ny 
S Yi] RR ) 
40% Ya 40% Yo! 
Se 20% 20% 
- 024 0% 
5 15 30 60 120 2 1 1. 30 60 2120 
$ Time, min b) Time, min 
100% 
80% 
pe 60% BE Yai 
8 ) 
0 40% Ya 
20% 
on™ 
) 15 30 60 
C, Time, min 
Fig.4: Effect of annealing time and temperature on the amount of decomposed 8-ferrite which is 
transformed in yy, ¥2i and o-phase. (a) 900°C, (b) 1050°C, (c) 1150°C. 
PT 
oF 
ted at 1150°C for short time. But, then the changes in parameters reflect the kinetics and intensity of 
the structure coarsening process. A closer examination of the Vy values obtained after prolonged 
annealing in Table 1 shows not only a stronger tendency of y,; formation at 1050°C, but also 
significantly faster kinetics of its formation. Initially, yi forms to a slightly larger extent than yap. In 
er the course of time the difference increases in favour of yy, so that after 30 minutes of annealing the 
hake volume fraction of intragranular 1,; becomes nearly equal to that of y,, Fig.4a. Although the amount 
of v5 is low, a high density of finely dispersed y»; caused an increase in the values of Sv, and