Achieving theoretical thermal conductivity and coeffieicent of thermal expansion in a W-Cu composite sheet

Abstract

W-20wt.%Cu composite sheets with full density and good surface quality were successfully fabricated through an infiltration process followed by a hot rolling. After a total thickness reduction of 75%, the majority of the tungsten (W) particles have been deformed and elongated along the rolling direction. The aspect ratio of the W particles in the composite has reached 2.5. The relative density increases considerably to a maximum value of 99.8% when the rolling ratio increases. The thermal conductivity and microhardness of the W-Cu composites increase significantly with the rolling reduction. On the contrary, the coefficient of thermal expansion (CTE) of the composite samples decreases with the rolling ratio. Specifically, after subjected to 75% of thickness reduction, we obtained a large W-Cu thin sheet. This thin sheet demonstrates a low CTE of 7.27×10^-6/K and the highest thermal conductivity of 224.91 W/(m-K); both values are close to the respective theoretical ones.