ZrB2-TiB2 Nanocomposite Powder Prepared by Mechanical Alloying

Diborides, including zirconium diboride (ZrB2) and titanium diboride (TiB2), have a number of desirable ceramic qualities that make suitable for preparing ceramic-matrix composites. However, synthesizing a composite based on these materials usually requires high temperatures and complex synthetic methods. In the present study, a nanocrystalline ZrB2-TiB2 powder was synthesized via mechanical alloying (MA) of the mixture of elemental Zr, Ti, and B powders mixed at a Zr/Ti/B mole ratio of 1:1:4, a 10:1 ball-to-powder weight ratio and 500 r/min rotational speed in a planetary ball-mill under argon atmosphere using a ZrO2 vial and balls. The effect of milling time on the phase change was investigated by X-ray diffraction (XRD), and the microstructure evolution of the powder mixture was monitored by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). It is found that after 120 h of milling, a nanoscale composite powder with ≈20 nm mean particle size can be obtained. Moreover, TEM examination clearly shows the composite powder is composed of the nanoscale TiB2 and ZrB2 particles. Finally, the milling mechanism was discussed.