FIGURE 2 Fracture appearances of creep ruptured specimens at (A, E) 600℃/925MPa, (B, F) 600℃/880MPa, (C, G) 600℃/850MPa, (D, H) 600℃/820MPa, (I, J) 600℃/805MPa, and (K, L) 600℃/790MPa.