The microstructure and radiation resistance of fine-grained W-0.3 wt%Y2O3 prepared by nano in-situ composite exposed to low-energy and high‑flux helium plasma

Abstract

Tungsten is facing extremely harsh irradiation environmental challenges as plasma-facing materials. In this work, W-0.3 wt%Y2O3 composites fabricated by nano in-situ composite method were subjected to He plasma irradiation with 60–80 eV and 2.88 × 1022–2.3 × 1026 m−2. The microstructure, morphology, and phase evolution on the surface before and after irradiation were systematically investigated. Besides, the damage behavior and mechanism were initially analyzed. Results show that the nano-scaled Y2O3 with the size of 40–350 nm dispersed uniformly at the grain boundary and within grains of matrix, and part of it formed orientation relationship of [1̅11] (1̅1̅0) W (bcc) // [011] (400) Y2O3 (bcc) with W to significantly improve the phase interface. Surprisingly, there is a semi-coherent relationship between W matrix and Y2O3 phase. Simultaneously, the fine-grained W-0.3Y2O3 composites reveals excellent resistance to He plasma irradiation. As the irradiation dose increases, the surface morphology evolves from smooth to roughening, micro-bulges, rod-shaped and swelling, however, no nano-fuzz are observed when the irradiation dose was up to 2.3 × 1026 m−2. Besides, the chemical constitution and phase composition on surface is unchanged. Moreover, the dislocation lines, loops and rafts are observed by TEM on the surface layer, but no He bubble is formed. The high irradiation resistance may be attributed to the formation channels to release He, which can provide a strategy and idea for designing anti-irradiation W materials.