Annealing effect on deuterium retention in W-Cr-Y alloy

Abstract

Deuterium (D) trapping in the W-11.4Cr-0.6Y alloy manufactured by field assisted sintering technology (FAST) and pre-annealed at temperatures of 1050, 1250, 1473 K was studied by in-situ thermal desorption spectroscopy (TDS). D incorporation in W-11.4Cr-0.6Y alloy was carried out by irradiation with deuterium ions (670 eV/D+) to a fluence of 5 × 1019 D/m2. The change in Cr concentration in the bulk of the W-Cr-Y alloy was studied using energy dispersive spectroscopy (EDS). The elemental composition on the surface of alloy samples before and after annealing was investigated using low energy ion scattering spectroscopy (LEIS). The Cr concentration increases on the surface of alloy sample during annealing at 1000 and 1050 K due to intensive Cr segregation, while it decreases at temperatures of 1250 K and above by dominant Cr sublimation. Pre-annealing of W-Cr-Y alloy at 1050 K leads to a decrease in the D trapping in the alloy which is connected with an increase in the Cr concentration on the surface. At high annealing temperatures of 1250 K and above, the appearance of new phases and decomposition-induced grain refinement leads to new types of defects with high binding energy for D.