Surface blistering and D desorption in high-energy-rate forging W, W-Y2O3, W-TiC exposed to deuterium plasma

Abstract

Pure tungsten (W) and two representative W alloys of W-1 wt.%Y2O3 and W-0.5 wt.%TiC were subjected to deuterium (D) plasma exposure at a fluence up to 1 × 1026 D/m2 at 400 K to evaluate their surface blistering and D desorption behaviors. Thermal desorption spectroscopy (TDS) results revealed that high-temperature desorption peaks (> 650 K) dominated in HERF-W, whereas the two W alloys featured higher intensities of low-temperature D desorption peaks (< 650 K). Even at a low D implantation fluence of 5 × 1023 D/m2, extensive blisters were evident on the surface of pure W, while no discernible blisters were detected on the surface of W-1 wt.%Y2O3 and W-0.5 wt.%TiC, even with a fluence exceeding 2 × 1025 D/m2. Microstructure analysis indicated that the relatively large grain size and limited intrinsic defects in HERF-W were the primary reasons for the early formation of D-induced blisters and subsequent high-temperature desorption of these trapped D, compared to those of two other W alloys. A focus ion beam (FIB)-SEM technique was employed to explore the mechanisms of blistering. Results revealed that the cavities beneath blisters were primarily located along grain boundaries, and coarse blisters were formed by the merging of several small ones. This work provides insight into the relationships among material microstructures, D-induced blistering and D desorption in W-based materials, thus offering valuable guidance for the design of W materials with high resistance to D-induced damages.