3D-printed CoNi high-entropy superalloy aims to let engines run hotter

An international research team has presented a new cobalt- and nickel-based high-entropy superalloy (CoNi-HESA), developed specifically for 3D printing using laser powder bed fusion (LPBF). The goal is to manufacture components for aircraft engines that operate reliably at higher operating temperatures, thereby improving efficiency and thrust.

Nickel-based superalloys have formed the backbone of modern turbine components for decades because they retain their strength even at high temperatures. Cobalt systems, on the other hand, excel in corrosion and oxidation resistance, but have so far been at a disadvantage in terms of high-temperature strength.

“The aerospace sector has long recognised the critical importance of increasing the maximum operating temperature of aircraft engines to enhance engine efficiency,” says Prof. José Manuel Torralba, Senior Researcher at IMDEA Materials and one of the authors involved in the publication. “As such, significant efforts have been devoted to the development of advanced metallic and intermetallic materials with exceptional performance capabilities.”

By combining both alloy families and the high-entropy alloy approach, CoNi-HESA was created, which exhibits both high high-temperature strength and ductility. The researchers used thermodynamic calculations based on mixing entropy to select the composition in such a way that a stable microstructure would form under LPBF conditions.

“With a careful combination of laser powder and scan speed in the LPBF process, the developed CoNi-HESA is well-suited for crack-resistant, high-density component production,” says Prof. Torralba.

A key factor was the adaptation of the LPBF process: by adjusting laser power, scan speed, powder bed heating and reduced layer thicknesses, the temperature gradient during the build could be lowered. This led to reduced residual stresses, less cracking and a more finely controlled microstructure. The resulting components show high densities and improved thermal and mechanical properties, as reported in the paper published in Materials & Design.

“As a final conclusion, we can state that the hypothesis, namely, that the design of CoNi- based superalloys through thermodynamic predictions based on mixing entropy can substantially improve material properties, has been confirmed. This is very promising for future additive manufacturing applications in fields such as energy, space and nuclear technology.”

In the long term, the authors see potential applications not only in aircraft engines, but also in power plants, space and nuclear technology. These sectors require materials that remain stable over long periods under extreme temperature and load conditions while still being suitable for additive manufacturing into complex geometries.

You can find out more about IMDEA Materials here.