Enhanced irradiation swelling resistance in low activation Ti8VCrMnFeCu2 high entropy alloys: Exploring the role of heterogeneous nanoparticles

Abstract

This study presents an in-depth analysis on the microstructural evolution of the low-activation Ti8VCrMnFeCu2 alloy under helium irradiation. The irradiation-induced vacancies and the change of Cu nanoprecipitates were characterized using slow positron-beam Doppler broadening spectroscopy (DBS) and transmission electron microscopy (TEM). It is revealed that the effective open volume of defects induced by helium irradiation was inhibited at room temperature even at a relatively high dose (3 × 101⁷ ions/cm2, ∼10.5 dpa). This is attributed to the formation of HemVn, which effectively decreases migration and aggregation of vacancies. Moreover, TEM results clearly illustrate the enhanced swelling resistance exhibited in the alloy. The estimated swelling rate is ∼0.092%/dpa with 1 × 101⁷ ions/cm2 at 723 K. This study demonstrates that Cu nanoprecipitates can effectively serve as traps for helium bubbles, as they capture helium atoms and inhibit their diffusion.

Keywords

• low activation
• BCC high entropy alloys
• Cu nanoprecipitates
• Positron annihilation
• Irradiation swelling