Mechanosynthesis of Hf 1− x Zr x B ₂ Solid Solution and Hf 1− x Zr x B ₂ /SiC Composite Powders

The synthesis of solid solutions in the HfB 2 –ZrB 2 system was conducted by mechanically induced self‐sustaining reaction (MSR) processes under an inert atmosphere from elemental mixtures of Hf, Zr, and B. The stoichiometry of the Hf 1− x Zr x B 2 solid solution phase was controlled by adjusting the Hf/Zr/B atomic ratio in the starting mixture. Composite materials with SiC were achieved by adding the required amount of SiC to the Hf/Zr/B reactant mixture. The presence of up to 20 vol% of SiC did not inhibit the MSR process. Longer milling times were required to ignite the mixture. Small amounts of the refractory phases ZrC or HfC were observed in the composite powders. The chemical composition, structure, and microstructure of products were studied by X‐ray diffraction, scanning and transmission electron microscopy, electron diffraction, and energy‐dispersive X‐ray spectroscopy. This complete characterization confirmed the formation of P 6/ mmm hexagonal diboride phases with a submicrometric microstructure. The determination of the chemical composition and lattice parameters ascertained the formation of solid solutions with good chemical homogeneity in the HfB 2 –ZrB 2 system.