AbstractThe design and development of the future generation of nickel base superalloys for the demanding environments of rocket engines should be based on the metallurgical and structural characteristics of theγ′phase. The distinctive features of this phase (e.g. strength, stability, size, shape, amount, distribution, uniformity, and order) can be controlled when a superalloy is appropriately designed and subsequently processed by an innovative solidification processing method. This concept has been successfully applied in the design and development of a superalloy. The resulting microstructure is almost perfect requiring no further treatment or processing.MST/1954