Microstructures and properties of Cu/Fe/Kovar composites prepared with cu-coated Kovar alloy powders

Abstract

To improve the thermal conductivities of Kovar alloys (4J50), Fe and Cu coatings were prepared on surfaces of one of Kovar alloys (4J50) powders by electroless plating and Cu/Fe/Kovar composites were hot-pressing sintered. The Fe interlayer is prepared to decrease the mutual diffusion between the Cu coating and the Kovar alloy matrix. Since the existence of Cu network in the composites, the composites present a better thermal conductivity than Kovar alloys. The Cu/Fe/Kovar composites containing 10 wt% and 20 wt% Cu have a thermal conductivity of 24.7 W/(m·K) and 25.8 W/(m·K), respectively, which is 48 % and 54 % higher than that of the Kovar alloy (16.7 W/(m·K)). Due to the presence of Cu network, the coefficients of thermal expansion of the composites is slightly higher than that of the Kovar alloy. The method reported in this study can be also applied to improve the thermal conductively of other Kovar alloys.