A LaB6-ZrB2 eutectic in situ composite was fabricated, using an electron beam zone heating technique, and oriented ZrB2 fibers in a LaB6 matrix were obtained. The range of diameters of the ZrB2 fibers was ∼0.2 to 1.2μm, with fiber lengths of up to 100μm. As the solidification rate increased, the interfiber spacing and fiber diameter decreased. Primary plate-like LaB6 dendrites formed upon the solidification of an ingot of hypoeutectic composition. The LaB6 was the first phase to nucleate when eutectic growth occurred, and ZrB2 exhibited non-faceted growth in the hypereutectic. For an ingot solidified with planar growth the orientation relationship of the phases was: growth direction: [001]LaB6||[00•1]ZrB2 and interfacial plane: (1¯10)LaB6||(11•0)ZrB2.

Structure Characteristics and Crystallography of LaB6-ZrB2 in situ Composite. Chen, C., Zhou, W., Zhang, L.: Progress in Natural Science, 1998, 8[1], 74-8. See also: Chinese Journal of Aeronautics, 1998, 11[1], 70-4, Journal of the American Ceramic Society, 1998, 81[1], 237-40 and Journal of Rare Earths, 1997, 15[4], 306-7