• Journal of Powder Materials
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• v.16 no.6
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• pp.442-448
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• 2009

$ZrB_2$-based composites are candidate materials for ultra-high temperature materials (UHTMs). $ZrB_2$ has become an indispensable ingredient in UHTMs, due to its high melting temperature, relatively low density, and excellent resistance to thermal shock or oxidation. $ZrB_2$ powders are usually synthesized by solid state reactions such as carbothermal, borothermal, or combined carbothermal reaction. SiC is added to this system in order to enhance the oxidation resistance of $ZrB_2$. In this study, $ZrB_2$?based composites were successfully synthesized and densified through two different processing paths. $ZrB_2$ or $ZrB_2$ 25 vol.%SiC was fully synthesized from oxide starting materials with reducing agents after heat treatment at 1400$^{\circ}C$. Besides, $ZrB_2$?20 vol.%SiC was fully densified with $B_4C$ as a sintering additive after hot pressing at 1900$^{\circ}C$. The synthesis mechanism and the effect of sintering additives on densification of $ZrB_2$ ?SiC composites were also discussed.

• Journal of Powder Materials
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• v.31 no.1
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• pp.30-36
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• 2024

The aerospace and power generation industries have an increasing demand for high-temperature, high-strength materials. However, conventional materials typically lack sufficient fracture toughness and oxidation resistance at high temperatures. This study aims to enhance the high-temperature properties of Nb-Si-Ti alloys through ball milling. To analyze the effects of milling time, the progression of alloying is evaluated on the basis of XRD patterns and the microstructure of alloy powders. Spark plasma sintering (SPS) is employed to produce compacts, with thermodynamic modeling assisting in predicting phase fractions and sintering temperature ranges. The changes in the microstructure and variation in the mechanical properties due to the adjustment of the sintering temperature provide insights into the influence of Nb solid solution, Nb5Si3, and crystallite size within the compacts. By investigating the changes in the mechanical properties through strengthening mechanisms, such as precipitation strengthening, solid solution strengthening, and crystallite refinement, this study aims to verify the applicability of Nb-Si-Ti alloys in advanced material systems.