Tuning heterogeneous ion-radiation damage by composition in NiFe_1- binary single crystals

Area of Science:

• Materials Science
• Nuclear Engineering
• Solid State Physics

Background:

• Radiation-induced heterogeneous damage is a major cause of failure in nuclear reactor components.
• Single crystal materials offer a potential solution due to the absence of grain boundaries.

Purpose of the Study:

• To investigate the effect of compositional tuning on the radiation tolerance of NiFe single crystal alloys.
• To understand the mechanisms behind improved resistance to irradiation-induced damage.

Main Methods:

• Preparation of [001] NiFe single crystals (x = 0, 0.38, 0.62 at% Fe) using the Bridgman method.
• Irradiation over a wide fluence range (4 × 10^13 to 4 × 10^15 ions/cm^2).
• Analysis using Rutherford backscattering/channeling spectrometry, Monte Carlo simulations, transmission electron microscopy, and nanoindentation.

Main Results:

• Ni0.38Fe0.62 single crystals exhibited superior radiation tolerance compared to pure Ni and Ni0.62Fe0.38.
• Transmission electron microscopy revealed defect agglomeration in Ni and Ni0.62Fe0.38, but not in Ni0.38Fe0.62.
• Compositional variations, specifically Fe atom arrangement, influenced both pristine and irradiated mechanical properties.

Conclusions:

• Compositional fine-tuning of NiFe single crystals is an effective strategy to mitigate radiation-induced heterogeneous damage.
• The improved radiation tolerance is linked to the suppression of defect accumulation zones.
• Understanding Fe atom arrangement is key to optimizing mechanical properties for nuclear applications.