Characterization of W/Fe functionally graded materials manufactured by resistance sintering under ultra-high pressure

• W/Fe functionally graded material (FGM) are fabricated well by resistance sintering under ultra-high pressure (RSUHP).
• The whole sintering time is less than 3 min and cost-effective.
• We research the W/Fe interface and the formation of intermetallic at the interface. In addition, we explain the possible method to avoid the formation of brittle intermetallic.
• Vickers hardness of W/Fe FGM before and after heat treatment are investigated here.

W/Fe-based components are considered as primary structural materials for the future fusion reactor. A five-layer W/Fe functional graded material (FGM) with W volume fraction of 0%, 25%, 50%, 75% and 100%, respectively, have been fabricated by a novel sintering method combining resistance sintering with ultra-high pressure. The sintering was carried out under pressures of 9 GPa and an input power of 11 kW for 60 s. The microstructure of cross-section observed by SEM shows a well-graded transition. The relative density of each layer is more than 97%. A brittle phase Fe7W6 is formed at the interface of W particles and Fe particles, and this intermetallic phase coats Fe particles homogeneously with a thickness of 1–5 μm. It is possible to avoid the brittle phase by choosing appropriate particle size and sintering parameters. In addition, Vickers hardness of W/Fe FGM was investigated before and after heat treatment.