Nickel-base superalloys making it possible to realize monocrystalline
parts with complex shapes, molded to dimension, are already used in ce
rtain advanced motors in the United States and France Several monocrys
talline superalloys have already been developed in France for the spec
ific needs of French motor mechanics in order to ensure their technica
l and commercial independence, Some important considerations and guide
lines of the development of these alloys are examined role of heat tr
eatments and optimal creep resistance obtained with relatively large p
recipitates (about 0.5 mum), solidification under high temperature gra
dient especially useful for reducing the porosity harmful to fatigue r
esistance of these alloys. The HIP treatment is an interesting techniq
ue for eliminating the porosity of monocrystals produced under low gra
dient in solidification installations. The effect of crystalline aniso
tropy in creep with respect to the microstructure and fatigue is exami
ned.