10. Relationships between structures and properties

Cobalt-based superalloys are mainly solid solution hardened. Their strength is not comparable to that of nickel-based superalloys. The latter, or iron-nickel-based superalloys used for the most critical applications, are hardened by γ' or γ'' precipitation in a face-centered cubic matrix, itself hardened by solid solution. The atomic percentage of γ' phase varies from 20 to 40% for conventional wrought alloys, and from 40 to 60% or even more for alloys obtained by powder metallurgy or casting.

The microstructure of components of a given chemistry is the result of the manufacturing process: elaboration, casting, forging, stamping, heat treatment, etc. The end of the process, and particularly the heat treatment, enables us to find the optimum properties in relation to the use of the component. The end of the process, and more specifically the heat treatment, enables...