In situ synthesis mechanism of ZrB2–ZrN composite

Abstract In situ ZrB 2 –ZrN composite was fabricated from Zr/BN powder blends by pressureless firing above 1600 °C with a pre-treatment in vacuum at 450 °C. The synthesis mechanism of ZrB 2 –ZrN composite was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. ZrN in the needle-like shape forms preferentially in the matrix at ca. 900 °C, followed by the appearance of ZrB, which is an intermediate phase in this reaction and will transform to ZrB 2 later at a relatively high temperature. The initially formed ZrN is most probably a non-stoichiometric compound with vacancies in the nitrogen site, noted as ZrN 1− x ( x 2 –ZrN composite.