Chemically Gradient Ordered Nanodomains Enable Large Tensile Ductility in Gigapascal Lightweight Refractory...

Area of Science:

• Materials Science
• Metallurgy
• Nanotechnology

Background:

• High-strength lightweight refractory alloys are crucial for high-temperature, high-stress applications like aero-engines.
• Current refractory alloys often suffer from low ductility, limiting their practical use.
• Developing materials with both high strength and ductility remains a significant challenge.

Purpose of the Study:

• To design and develop exceptionally ductile and high-strength lightweight refractory high-entropy alloys (RHEAs).
• To introduce a novel architectural concept using chemically gradient ordered nanodomains (CGONs) to enhance material properties.
• To guide the development of advanced refractory materials for demanding engineering applications.

Main Methods:

• Introduction of dispersed, chemically gradient ordered nanodomains (CGONs, 1-3 nm) coherent with the disordered matrix.
• Design of CGONs with gradual chemical composition variation from shell to core.
• Fabrication and characterization of an Nb-Zr-Ti-Ta-Al based RHEA.

Main Results:

• Achieved a low mass density of 6.48 g/cm³.
• Demonstrated high yield strength exceeding 1.0 GPa at room temperature.
• Obtained significant tensile elongation (21.5% uniform, 47.8% to failure), indicating extraordinary ductility.
• CGON architecture enhanced thermodynamic stability and facilitated stress transfer, reducing interfacial strain.

Conclusions:

• The novel CGON design successfully yields ductile and ultra-strong lightweight refractory high-entropy alloys.
• Enhanced thermal stability of CGONs contributes to excellent high-temperature performance.
• This approach provides a pathway for developing advanced refractory materials for critical engineering applications.