Effect of High Temperature Air-Exposure on Room Temperature Fatigue Crack Growth of Ni-Base Single Crystal Superalloy CMSX-10
Room temperature fatigue crack growth behaviour of un-exposed(as-received) and high temperature air-exposed(at 1100°C for 24 to 1000 h) CMSX-10 was investigated. A small compact tension specimen with  loading direction and  fatigue crack growth direction was used. The fatigue crack growth results were analyzed using a stress intensity parameter K . It is shown that the air-exposure has no deteriorative effect on the crack growth behaviour, even though the microstructure has changed by the exposure(coarsening of γ' ). The crystallographic facet fracture of (1-11) and (-111) planes appeared and the intersection of the planes forms sets of lines(ridge and valley) parallel to  direction. The fatigue crack tip front is schematically shown.
Kikuo Kishimoto, Masanori Kikuchi, Tetsuo Shoji and Masumi Saka
Y. Iino, "Effect of High Temperature Air-Exposure on Room Temperature Fatigue Crack Growth of Ni-Base Single Crystal Superalloy CMSX-10", Key Engineering Materials, Vols. 261-263, pp. 1191-1196, 2004