W-3 wt%Sm2O3 composite powders were formed by mechanical alloying for 5 h. The powders were consolidated by spark plasma sintering (SPS) at 1800 degrees C to suppress grain growth during sintering. Microstructure and properties of W-3 wt%Sm2O3 composites were investigated by scanning electron microscopy, transmission electron microscopy, microhardness test, and thermal conductivity test. The grain size, relative density of the W-3 wt%Sm2O3 composites were 3-4 mu m and 91%, respectively. As the temperature rises from 25 to 800 degrees C, the thermal conductivity of W-3 wt%Sm2O3 composites increased and the thermal conductivity of the samples was above 170 W/m K at room temperature. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B. V. and The Society of Powder Technology Japan. All rights reserved.