Nano-in-situ-composite ultrafine-grained W–Y2O3 materials: Microstructure, mechanical properties and high heat load performances

Abstract

Tungsten has been confirmed as an idea plasma-facing material in future nuclear fusion reactor, however, existing commercial tungsten material can not meet the extremely high heat load environmental because its coarse grain and low toughness. In this work, fine-grained W–Y2O3 materials were prepared by nano-in-situ composite method. The microstructure, mechanical properties and strengthening mechanism were analyzed. Meanwhile, the effect of adding Y2O3 content on the properties was systematically investigated. Besides, the damage behavior and failure mechanism of the W–Y2O3 composites were studied exposed to the transient high thermal load. Results show that a very fine and homogenized microstructure was obtained, the average W grain size is about 1.7 μm, which tends to increase with rising of the content of Y2O3, while the Y2O3 particle with size of 80–150 nm evenly dispersed in the W matrix. It is worth noting that a coherent relationship was observed between Y2O3 the W matrix by the forming of a (Y, W) O composite, improving the interface compatibility between W matrix and Y2O3 ceramic phase. Accordingly, a synergistic effect of fine-grained strengthening, dispersion strengthening and coherent strengthening has been brought by nano-in-situ composite, which plays an effective role in enhancing W mechanical properties. The maximum tensile strength and elongation at RT is about 520 MPa and 1.5%, while they are 415 MPa and 8.3% at 400 °C, respectively. Moreover, high heat load tests show that nano-in-situ-composite W–Y2O3 material has excellent high thermal-shock resistance, it can endure 600 MW/m2 thermal shock without any cracks, which is demonstrably superior to the traditional commercial tungsten value.