New microstructural concepts to optimize the high-temperature strength of gamma'-hardened monocrystalline nickel-based superalloys

Monocrystalline gamma'-hardened nickel-based superalloys frequently exhibit directional coarsening, i.e. so-called rafting, accompanied by softening during high-temperature creep and fatigue. The objective of the present work is to seek new microstructural concepts in order to optimize the high-temperature creep and fatigue strength by suitable measures to prevent rafting and by exploitation of the directionality of intentionally introduced raft structures. Preliminary experiments indicate that this approach can lead to improved material behaviour. (C) 1997 Elsevier Science S.A.