Self‐propagating mechanosynthesis of HfB2 nanoparticles by a magnesiothermic reaction

A mechanically induced self‐sustaining reaction (MSR) was used to synthesize hafnium diboride nanoparticles. Along this route, magnesium was selected as a robust reducing agent for co‐reduction in boron and hafnium oxides in a combustive manner. Combustion occurred after a short milling period of 12 minutes. The hafnium diboride nanoparticles had a polygonal faceted morphology and were 50‐250 nm in diameter. The assessment of the processing mechanism revealed that the initial combustive reduction in B₂O₃ to elemental B by Mg was the major step for progressing the overall reaction. After that, HfO₂ can be reduced to elemental Hf, followed by the synthesis of HfB₂ phase.