In this work, to improve the strain capacity of tungsten , β-SiC was added to form W-Si-C multi-phase composites composed of W, W 2 C, and W 5 Si 3 using the arc-melting method. The relationship between microstructure and mechanical behavior was investigated, and a microstructural evolution mechanism was proposed. The grain size of the W was refined significantly from 1071.8 to 5.4 µm as the SiC content increased. The micro-hardness (3.67–12.79 GPa) and ultimate compressive strength (UCS) (0.90–2.29 GPa) of the W-Si-C multi-phase composite obviously increased as the β-SiC content increased to 4 wt% due to the grain refinement and segregation of the W 2 C and W 5 Si 3 at the grain boundaries. The highest strain of UCS (21.9%) was obtained at 1 wt% SiC, which is three times of that of pure W (7.4%) and is a result of the refined W grain size and the potentiation of W 5 Si 3.
The SiHfOC ceramic microspheres were synthesized from the polysilazane and hafnium(IV) acetylacetonate hybrid precursors through a combination of hydrothermal method and polymer-derived ceramics (PDCs) method. The SiHfOC ceramic microspheres consist of β-SiC, SiO 2 , and m -HfO 2 in an amorphous SiOC matrix and are in a spherical morphology with an average size of about 2 μm. Hafnium-containing nanoparticles with ∼50-nm size are not only uniformly distributed on the surface of the ceramic microspheres but also embedded in the SiHfOC ceramic microspheres, forming a unique mosaic structure. Pyrolyzing at 1000°C offers a possibility of an in situ formation of nanocrystal nuclei in the amorphous SiOC ceramic matrix, and the subsequent annealing at 1500°C helps the small nanocrystal nuclei grow and separate the amorphous SiHfOC into a multiphase SiOC network containing β-SiC, SiO 2 , m -HfO 2 nanocrystalline and free C. This research provides a methodology for preparing multicomponent ceramic microspheres that can efficiently develop high-performance PDCs modified by transition metal alkoxide.
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