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用电子束悬浮区熔法制备了LaB_6-ZrB_2共晶自生复合材料,其组织为LaB_6基体上均匀分布着直径为0.2～1.2μm的ZrB_2纤维,纤维长度可达100μm以上.随着凝固速度的增加,纤维直径和间距随之减小,单位面积上的ZrB_2纤维数可达到10~8/cm~2。对于固液界面为平面生长的试样,其结晶学取向关系为[001]_(LaB_6)//[0.01]_(ZrB_2),(110)_(LaB_6)//(11.0)(ZrB_2).在亚共晶组织中,LaB_6为初生相,呈小平面方式生长,共晶组织依附着LaB_6生长;在过共晶组织中,初生相ZrB_2以非小平面方式生长.
LaB_6-ZrB_2 eutectic composites were prepared by electron beam suspension zone method, the microstructure of the composites was homogeneous distribution of ZrB_2 fibers with diameter of 0.2 ~ 1.2μm on LaB_6 matrix, and the fiber length was over 100μm. With the increase of solidification rate , The diameter and spacing of fibers are reduced, and the number of ZrB 2 fibers per unit area can reach 10 ~ 8 / cm ~ 2. The crystallographic orientations of the specimens with flat growth at solid-liquid interface are [001] _ (LaB_6) // [0.01] _ (ZrB_2), (110) _ (LaB_6) // (11.0) (ZrB_2). In the hypoeutectic structure, LaB_6 is the primary phase and grows in a small plane manner. The eutectic structure is dependent on LaB_6 growth. In the hypereutectic structure, the primary phase ZrB_2 grows in a non-faceted manner.