Structure characteristics and crystallography of LaB₆-ZrB₂ in-situ composite

LaB₆-ZrB₂ eutectic in-situ composite was fabricated by use of an electron beam zone heating technique, and orientated ZrB₂ fibers in a LaB₆ matrix were obtained. The range of diameter of the ZrB₂ fibers was ∼ 0.2-1.2 μm, with fiber lengths up to 100 μm. As the solidification rate increases, the interfiber spacing and fiber diameter decrease. Primary plate-like LaB₆ dendrites formed upon the solidification of an ingot with hypoeutectic composition. LaB₆ was the first phase to nucleate when eutectic growth occurred, and ZrB₂ showed non-faceted growth in the hypereutectic. For the ingot solidified with planar growth the orientation relation of the phases was Growth direction: [001]LaB₆// [00.1]ZrB₂, Interfacial plane: (1̄10)LaB₆//(11.0)ZrB₂.