NEW MICROSTRUCTURAL CONCEPTS TO OPTIMIZE THE HIGH-TEMPERATURE STRENGTH OF GAMMA'-HARDENED MONOCRYSTALLINE NICKEL-BASED SUPERALLOYS

Monocrystalline gamma'-hardened nickel-based superalloys frequently ex hibit directional coarsening, i.e. so-called rafting, accompanied by s oftening during high-temperature creep and fatigue. The objective of t he present work is to seek new microstructural concepts in order to op timize the high-temperature creep and fatigue strength by suitable mea sures to prevent rafting and by exploitation of the directionality of intentionally introduced raft structures. Preliminary experiments indi cate that this approach can lead to improved material behaviour. (C) 1 997 Elsevier Science S.A.