Influence of Nb content on the microstructure and deuterium retention of W–Nb alloys

Abstract

W–Nb alloys were prepared using machine milling and spark plasma sintering. Field–emission scanning electron microscopy, high–resolution transmission electron microscopy were used to characterize the samples. Thermal desorption spectroscopy was used to measure the deuterium retention. Results indicated that the interdiffusion between W and Nb occurred during high temperature sintering and formed Nb(W) solid solution. The grain size decreased with Nb content increased, and porosity of W–Nb alloys was decreased significantly compared to W bulk. Hence, Nb alloy had a significant effect on promoting W-based material densification. The microhardness increased as Nb content increased, which was ascribed to fine grain and low porosity. D retention in W–Nb alloys was higher than that in pure W (D2+ flux ∼ 1021m−2 s−1, ion energy ∼5 KeV).Total D retention increased as Nb content increased, which was ascribed to the density of grain boundaries that increased as Nb content increased and higher affinity between Nb and D.