Continuous WCu functional gradient material from pure W to WCu layer prepared by a modified sedimentation method

Abstract

The thermal stress between W plasma-facing material (PFM) and Cu heat sink in fusion reactors can be significantly reduced by using a WCu functionally graded material (WCu FGM) interlayer. However, there is still considerable stress at the joining interface between W and WCu FGM in the W/WCu FGM/Cu portions. In this work, we fabricate W skeletons with continuous gradients in porosity by a modified sedimentation method. Sintering densification behavior and pore characteristics of the sedimented W skeletons at different sintering temperatures were investigated. After Cu infiltration, the final WCu FGM was obtained. The results indicate that the pore size and porosity in the W skeleton decrease gradually with the increase of sintering temperature, but the increase of skeleton sintering temperature does not reduce the gradient range of composition distribution of the final prepared WCu FGM. And WCu FGM with composition distribution from pure W to W-20.5wt.% Cu layer across the section was successfully obtained. The thickness of the pure W layer is about one-fifth of the whole sample thickness. In addition, the prepared WCu FGM has a relative density of 94.5 % and thermal conductivity of 185 W/(m • K). The WCu FGM prepared in this work may provide a good solution to alleviate the thermal stress between W PFM and Cu heat sink in the fusion reactors.

Keywords

• W skeleton
• W
• Cu composites
• Continuously functional graded materials
• Pure W layer
• Porosity distribution