Structure and properties of La0.6Ce0.3Pr0.1B6-ZrB2, a directionally solidified eutectic with different growth rates

La0.6Ce0.3Pr0.1B6-ZrB2, a directionally solidified eutectic (DSE), is a material with a high-performance thermionic emission with great application prospects. The influence of the growth rates of this DSE on the microstructure, growth direction, two phases orientation relationship, mechanical properties, and thermionic emission properties was investigated. The experimental results show that the microstructure and growth direction of the two phases varied with the growth rate of the eutectic: the faster the growth rate, the lower the uniformity of the ZrB2 phase became, and the growth directions of the La0.6Ce0.3Pr0.1B6 matrix and the ZrB2 phase were also altered accordingly. In the La0.6Ce0.3Pr0.1B6-ZrB2 DSE with a growth rate of 100 mm/h, the two phases have a unique growth direction and a crystallographic orientation relationship. The fracture toughness of the La0.6Ce0.3Pr0.1B6-ZrB2 DSE is at least 50% higher than that of the single crystal La0.6Ce0.3Pr0.1B6, and the fracture toughness of the DSEs formed at different growth rates also differed.

Automated summary

The growth rate of La0.6Ce0.3Pr0.1B6-ZrB2 eutectic material affects its microstructure, mechanical properties, and thermionic emission performance. A higher growth rate leads to lower uniformity of the ZrB2 phase, resulting in increased fracture toughness of the material.