Preparation of W–TiC alloys from core–shell structure powders synthesized by an improved wet chemical method

Abstract

In order to improve the homogeneous distribution of the TiC particles and facilitate the TiC particles to distribute in the tungsten grain interiors, two kinds of TiC-doped tungsten precursors with a core–shell structure were prepared by an improved wet chemical method at different reaction temperature conditions. Consequently, fine plate-like precursor (200–400 nm) and flower-like precursor (approximately 1.25 μm) are obtained. After reduction and sintering, the microstructures of the samples were characterized by scanning electron microscopy and transmission electron microscopy. In the sample sintered from the plate-like precursor, TiC particles with sizes in the range of 40–300 nm and an average size of approximately 80 nm were uniformly distributed in the tungsten matrix with a high share in the grain interiors. However, in the sample sintered from the flower-like precursor, the TiC particles with sizes in the range of 50–700 nm are significantly aggregated and non-uniformly distributed in the tungsten matrix. As a result, the sample sintered from the plate-like precursor achieves higher mechanical properties and a much narrower range of bending strength values than that sintered from the flower-like precursor. The average bending strength of the sample sintered from the plate-like precursor is 655 MPa, which is higher than that of the sample sintered from the flower-like precursor (524 MPa). Different reaction mechanisms and dispersing stabilities of the TiC particles at different temperature conditions should be accounted for the differences between the two samples.