Response of Dispersion-Strengthened Tungsten Alloys to Helium Irradiation

Helium ion irradiation is a major threat to the integrity of tungsten materials as plasma facing components, since the generated He bubbles can substantially degrade the material mechanical, thermal, and surface properties. In this talk, we will focus on the response of dispersion-strengthened tungsten (DS-W) alloys to helium irradiation. DS-W is a new class of W alloys strengthened by carbide dispersoids, such as TiC, ZrC and TaC. Compared to pure W, DS-W possesses increased recrystallization temperature and improved ductility, making DS-W promising candidates as divertor materials of future fusion reactors. Our studies showed that He bubble formation in DS-W was suppressed by the carbide dispersoids. In DS-W alloys irradiated at 800°C to the fluence of 1×10²⁴ He/m², no bubbles were founded within the carbide particles or at the carbide-W interface, while obvious bubbles formed in the W matrix. Similar phenomenon was observed using in-situ He irradiation conducted at 950°C, suggesting the capability of carbide dispersoids to trap He atoms as small clusters. Thermal desorption spectroscopy analysis discovered that the thermal release of implanted He decreased as carbide concentration increased from zero to 10 wt.% in DS-W. Microscale mechanical testing found that TiC-strengthened W showed better mechanical performance than pure W and other DS-W alloys after He irradiation. Our study provides a new avenue to designing W alloys with superior tolerance to He irradiation by optimizing the dispersoid concentration and distribution.