The precipitation of topologically close-packed phases in rhenium-containing superalloys

Most modern single crystal alloys are thermodynamically unstable with respect to the formation of topologically close-packed (TCP) phases due to the addition of solid solution strengtheners, such as rhenium, molybdenum and tungsten. The occurrence, nucleation and growth of TCP phases in a number of rhenium-containing second generation alloys have been studied. It has been found that all the alloys form the σ phase; in some cases as a meta-stable...