Microstructure and mechanical properties of tungsten fiber reinforced tungsten composites prepared by Fe activated sintering

Tungsten fiber reinforced tungsten composites were fabricated by Fe activated sintering. The effect of Fe content (0.5% similar to 1.0%(wt%)) and original fiber volume fraction (10% similar to 50%(vol%)) on relative density, microstructure and mechanical properties were studied. The interaction between the Fe and tungsten fiber was analyzed. The fracture behavior as well as the strengthening and toughening mechanisms were revealed. The results indicated that the Fe not only promoted the sintering densification of the tungsten matrix, but also caused the recrystallization of tungsten fiber from the surface to the center due to the element diffusion. The (i) relative density, (ii) residual fiber diameter (or residual fiber volume fraction) and (iii) flexural strength were (i) increased, (ii) decreased and (iii) increased with Fe content increased, respectively, while were (i) decreased, and (ii, iii) first increased and then decreased with the original fiber volume fraction increased, respectively. As for the composites containing 1.0%Fe, the fracture toughness was monotonically increased with the increase of the original fiber volume fraction. The fracture mode of the matrix was intergranular. The strength and toughness of the composites were enhanced as a result of fiber fracture, crack deflection, interface debonding, and fiber pull-out.