Microwave sintering of W/Cu functionally graded materials

Fabricating W/Cu functionally graded materials (FGM) with fine microstructure and good properties is extremely significant in the development of fusion reactors as well as spallation neutron sources. The five-layered W/Cu FGM (W30% + Cu70%/W50% + Cu50%/W70% + Cu30%/W90% + Cu10%/W100%, volume fraction) were fabricated by a microwave sintering method in a short time (30 min). Scanning electron microscopy and energy dispersive X-ray spectrometer analysis showed that the graded structure can be retained although the microwave sintering temperature was as high as 1300 °C (well above the melting temperature of Cu) and the fine microstructure of W in each layer can be also maintained due to the short sintering time. The overall relative density of the W/Cu FGM sample microwave-sintered at 1350 °C reaches 93% and the copper-rich layers are almost 100% dense. The thermal conductivity of the sample is about 200 W/mK at room temperature and decreases with increasing temperature.