The Microstructure and Mechanical Properties of Carbon Nanotube-Reinforced W-Matrix Composites

W-(0.03 wt.%, 0.5 wt.%) CNTs composites with good mechanical properties and high density were prepared by spark plasma sintering. The microstructure and the phase distribution of the W matrix composite powder and the sintered samples were analyzed by scanning electron microscopy and x-ray diffractometer. The mechanical properties of the W matrix composite, including microhardness and compressive strength, were tested and evaluated. The CNTs addition improves the densification kinetics and the relative densities of the materials are above 95%. The addition of the CNTs refined the grains of matrix W, and the grains became finer with the increase in CNTs content. The second phase of W₂C was formed in the composite material. Thermodynamic calculation showed that the formation reaction of W₂C was a spontaneous endothermic reaction at high temperature. With the increase in CNTs content, the production of W₂C increased. The microhardness and compressive strength of W-CNTs composites were effectively improved under the combined effect of grain refinement and second phase strengthening. The microhardness and compressive strength of the composites with 0.5 wt.% CNTs were 434 MPa and 1746 MPa, respectively, and the compressibility was 10.74%. The strength and compressibility of CNTs-W matrix composites were improved simultaneously.