Which superalloys are commonly used in single crystal casting for turbine blades?

First- and Second-Generation Alloys

Early single-crystal turbine blade development was built around first- and second-generation alloys such as PWA 1480 and CMSX-2. These alloys eliminate grain boundaries and incorporate modest levels of refractory elements to enhance creep resistance and fatigue life. They were widely adopted for early high-pressure turbine blades in commercial and military engines where higher temperature capability was required compared with polycrystalline designs.

Third-Generation Superalloys

Third-generation alloys significantly increase rhenium content to improve high-temperature strength. Key examples include PWA 1484, CMSX-4, and Rene N5. These alloys deliver exceptional creep resistance, oxidation stability, and thermal fatigue performance, enabling turbine inlet temperatures well above 1,000°C. Their balanced chemistry makes them a standard choice for modern aerospace engines.

Fourth- and Fifth-Generation Technologies

To push engine efficiency further, fourth- and fifth-generation alloys introduce advanced refractory elements such as ruthenium, improving phase stability under extreme thermal loads. Examples include TMS-138, TMS-162, and Rene 142. These alloys provide unparalleled creep performance and oxidation resistance, supporting the next generation of high-thrust aerospace and power generation turbines.

Emerging Ultra-High-Temperature Alloys

Advanced research alloys such as EPM-102 and TMS-196 push performance into ultra-high-temperature regimes. These formulations refine microsegregation behavior and offer superior resistance to phase instability during prolonged service. Although not yet as widespread as CMSX or PWA alloys, they represent the technological direction for future turbine blade materials.