Irradiation-Induced Phase Stability in Ti- and Nb-Containing Nickel-Based High-Entropy Alloys at 500 °C

Area of Science:

• Materials Science
• Nuclear Engineering
• Metallurgy

Background:

• High-entropy alloys (HEAs) are promising for nuclear applications due to their unique properties.
• Understanding their response to irradiation is crucial for developing radiation-tolerant materials.

Purpose of the Study:

• To compare the irradiation response of two L12-strengthened HEAs: (Ni2Co2FeCr)92Ti4Al4 (TiHEA) and (Ni2Co2FeCr)92Nb4Al4 (NbHEA).
• To investigate the role of solute additions (Ti vs. Nb) in determining the microstructural stability and mechanical properties under irradiation.

Main Methods:

• 6.4 MeV Fe3+ irradiation at 500 °C up to 30 dpa.
• Microstructural analysis using Transmission Electron Microscopy (TEM) and Atom Probe Tomography (APT).
• Mechanical property evaluation via nanoindentation.

Main Results:

• TiHEA maintained L12-ordered structure and compositional stability better than NbHEA under irradiation.
• TiHEA exhibited a higher irradiation hardening rate (27%) compared to NbHEA (23%).
• Distinct solute-defect interactions were observed: Ti facilitated vacancy mobility, while Nb acted as a vacancy trap.

Conclusions:

• Solute addition critically influences the radiation tolerance of L12-strengthened HEAs.
• Ti-containing HEAs demonstrate superior resistance to irradiation-induced microstructural degradation and hardening.
• These findings guide the design of advanced radiation-tolerant high-entropy alloys.