Crack Paths 2009

10-2

10-6

(a)

(b)

Kmax [MPa√m]

10-6543

1-100-1 AR, 28%, 207nm 72 0-1AR,28%, 207nm 720 - , 46%, 97nm 2 0-1,26%, 258nm 1 0 1,15%,208nm 9 130

10-7

1-100-1AR,28%, 207nm

1-7200-1AR,28%, 207nm

1-7200-1, 46%, 97nm

1-7200-1, 26%, 258nm

1-100-1, 15%, 208nm

1-100-1,19%,130nm

10-8

20

30 40 50 60 70

20

30 40 50 60 70

ΔK [MPa√m]

Figure 4: a) Crack growth rate as a function hold time for tests conducted at 650oC, and

b) Effects of γ’S statistics on da/dt for tests conducted at 650oC

(a)

(a)

(b)

Figure 5: a) Typical grain boundary crack path showing secondary cracking (as

received, 1s-7200s-1s, 650ºC), and b) typical intergranular fracture surface

corresponding to dwell time tests (as received, 1s-7200s-1s, 650ºC)

933

5