Spinodally reinforced W-Cr fusion armour

Abstract

Here, we introduce a discontinuous spinodal reinforcement strategy in the novel candidate plasma facing material (PFM) of tungsten-chromium alloys. Thermal ageing of a W-34wt%Cr alloy at 1250 °C causes nano-scale lamellae 200–600 nm to form heterogeneously from grain boundaries, which progressively grow into the matrix fully, then coarsen to 1–2 µm after 100 h. The dual-phase microstructure confers exceptional high temperature compressive strength, maintaining 900 MPa at 1000 °C - double that of polycrystalline tungsten. Further, the chromium alloying promotes a dense oxide scale that confers a 2 orders of magnitude improvement in resistance against oxidation at 1000 °C compared to W, which is an important consideration for PFMs under loss of vacuum accident conditions. The dual-phase W-Cr alloy concept's combination of high strength and oxidation resistance represents a new scalable alternative to tungsten, with wide scope for further alloying and process optimisation.