Effect of interface modification by Cu-coated W powders on the microstructure evolution and properties improvement for Cu-W composites

The effects of interfacial bond and homogeneous microstructure on the physical properties of Cu-W composites have been investigated. To acquire strong interfacial bond and homogeneous microstructure, different modified W powders have been designed, which W powders were coated with different Cu contents using electroless plating method. The results showed that by increasing the Cu content of the coating, the microstructure of Cu-W composites becomes homogeneous, and the physical properties, including thermal, electrical and mechanical properties, improved greatly. When 20Cu@W composite powders were used to fabricate Cu-W composites, the physical properties reached the optimal values: The thermal conductivity was 239 W/(m.K) which was close to the theoretical vaule of 240 W/(m.K), the electrical conductivity was 50.6%IACS, coefficient of thermal expansion was the minimum value of 73 x 10(-6)/K, the bending strength and Vickers hardness were 976.7 MPa and 224.8 HV, respectively. These optimal values were much higher than those of mixed Cu-W composites. The properties enhancement of Cu-W composites is attributed to the strong interfacial bond between Cu and W and homogeneous microstructure. This enhancement effect was strengthened by increasing the coating's Cu content, resulting in the continuous improvement of the physical properties. (C) 2016 Elsevier B.V. All rights reserved.