Which high-temp alloys are commonly paired with TBC in aerospace?
Alloy Selection for TBC Integration
In aerospace applications, TBCs are typically paired with nickel-based and advanced titanium alloys that operate near their thermal limits. Nickel superalloys are most widely used due to their high γ′ strengthening phase and excellent creep resistance. Alloys such as Inconel 718, Inconel 738LC, and high-performance series like CMSX-4 and PWA 1484 are ideal substrates for TBC because they maintain structural integrity at elevated temperatures while benefiting significantly from thermal protection.
These materials are often chosen for turbine blades, vanes, and combustor liners, where TBC allows higher operating temperatures beyond the alloy’s melting or creep threshold.
Single Crystal and Directionally Solidified Alloys
For the most demanding aerospace engine stages, single crystal and directionally solidified alloys provide superior creep resistance and grain-boundary stability. Alloys used in single crystal casting—such as Rene N5, TMS-138, and RR3000—are commonly paired with TBC in high-pressure turbine stages. TBC reduces thermally induced stresses and mitigates phase instability under long-term exposure to combustion gases.
Directional cast alloys used in superalloy directional casting can also benefit from TBC to protect grain boundaries from crack initiation during thermal cycling.
Titanium Alloys in Hot Sections
While titanium alloys are typically used in cooler engine zones, high-performance types such as Ti-6Al-4V and advanced versions like Ti-5Al-5V-5Mo-3Cr (Ti5553) are increasingly used in hotter zones when combined with TBC. Coatings help prevent oxidation and enhance thermal fatigue resistance, especially in compressor stages and structural housings.
When paired with precise superalloy CNC machining, titanium alloys achieve weight reduction without sacrificing durability.
Application Prioritization
Depending on the engine section, different alloys are selected in combination with TBC:
High-pressure turbine blades → CMSX/ Rene/ PWA single-crystal alloys
Combustor liners → Inconel 713C / 738LC
Compressor and structural parts → Ti-6Al-4V or Ti5553 with moderate TBC
All of these components rely on TBC not only for heat protection but also for lifespan extension and reduced creep deformation.
