Directional solidification, nanoindentation and thermionic properties of LaB₆(100)-ZrB₂ eutectic composite

LaB₆ (100)-ZrB₂ eutectic composite was directionally solidified by optical floating melting zone at solidification rate V= 100 mm/h. It was shown that the stable eutectic growth can be achieved by periodic diverging and convergent growth, indicating that eutectic spacing was not unique value, but existed a limited range under a given rate. The atoms of the LaB₆ (100)/ZrB₂ interface were directly bonded. The mechanical property of the individual eutectic phase was evaluated by the nanoindentation. Both average Berkovich hardness and elastic modulus of LaB₆/ZrB₂ phases was higher than that of LaB₆ phase. Thermionic emission of DS LaB₆(100)-ZrB₂ eutectic obeyed the Longo theory, indicating only the metal ceramic of LaB₆ matrix in the composite emitted the electron. The practical work function distribution of DS LaB₆(100)-ZrB₂ eutectic composite ranged from 2.51 to 3.18