Rapid consolidation of ultrafine grained W-30 wt.% Cu composites by field assisted sintering from the sol-gel prepared nanopowders

W-30 wt.% Cu composite powders with homogenous distribution of W and Cu nanoparticles were successfully synthesized by a sol-gel procedure combined with hydrogen reduction. These ultrafine particles smaller than 150 nm exhibited favorable sinterability when densified by field assisted sintering technique (FAST) at the temperatures below the melting point of Cu. Moreover, the as-sintered composites inherited the ultrafine and homogeneous characteristics of the initial particles. The final densities of the sintered samples showed a strong dependence on the sintering temperature and applied pressure. By increasing the sintering temperature or pressure, denser composites with higher thermal conductivity and lower coefficient of thermal expansion (CTE) could be obtained. Specifically, the samples sintered at 950 °C under 120 MPa for 10 min achieved a maximum relative density of 97.3%, exhibiting an excellent thermal conductivity (235.48 W/(m K)) and a relatively low CTE of 9.27 × 10⁻⁶/K.