Crack Paths 2006

10-5

300K

2024AT351 air

2022T351air

2022T851air

-6

10

2024AT351vacuum

2022T351vacuum

2022T851vacuum

-7

10

-8

10

10-9

10-10

-11

10

4 6

8

10

30

' K(MPa.m1/2)

a)

-5

10

223K

2024AT351 air

2022 T351 air

2022 T851 Air

-6

10

2024AT351 Vacuum

2022 T851 Vacuum

2022 T351 Vacuum

-7

10

-8

10

10-9

10-10

10-11

4 6 8 10

30

' K(MPa.m1/2)

b)

Figure 4: Crack propagation curves da/dN vs ' Kin ambient air and high vacuum

at room temperature (a) and 223K(b).