1. Creep-Resistant Steels

3. Z-phase, inaccurate data

6. Thermodynamics Cannot win, can only break even
Can only break even at absolute zero
Self evident truth, statement which commands general belief, an unverifiable although widely accepted fact
Cannot reach absolute zero

7. Goal
Increase as far as is possible, the maximum temperature in the cycle
i.e. better materials & engineering
Self evident truth, statement which commands general belief, an unverifiable although widely accepted fact

10. Taylor & Thornton, ALSTOM Power, Rugby

11. 0.5 µm

15. b a
time = t+∆t
time = t

17. 2.25Cr1Mo 600°C

19. Yamasaki & Bhadeshia, 2003

24. x

27. Coarsening diffusion r r flux concentration q a q aq c r aq c r1 2
flux q a q
concentration aq c r 1 aq c r 2
distance

28. Mean radius / m Time / s Number density Time / s10 -9 -8 -7 -6
1/3
Mean radius / m
1/2 10 9 8 7 6 5 4 3 2
Time / s 2 4 -3
Number density 18 m 10 9 8 7 6 5 4 3 2
Time / s
Fujita & Bhadeshia, 2000

29. Data from Abe, 1999 Fe-9Cr-W alloys M_23C_6 size / µm10 -2 -1 1
Data from Abe, 1999
Fe-9Cr-W alloys
0W 1W 2W 4W
M_23C_6 size / µm 10 4 3 2 1
Time at 600 °C / h

30. Mole fraction of phase 0.00 0.01 0.02 0.03 M_23 C_6 Laves phase 5 4 3
Tungsten / wt%

31. Multicomponent coarsening
Venugopalan & Kirkaldy, 1978

32. Coarsening accelerated by tungsten-1 2
chromium alone
Effective diffusivity / m s
multicomponent 5 4 3 2 1
Tungsten / wt%

33. Multiphase coarsening ?
Laves
concentration
in ferrite q q
distance

35. 650 oC
Cole & Bhadeshia, 2002