Theoretical Strength of Borides and Quasibinary Boride Eutectics at High Temperatures

The theoretical strength of LaB 6 and MeB 2 borides and a eutectic LaB 6 –TiB 2 system is calculated with quasiharmonic approximation for uniaxial strain in the temperature range between 0 and 2750 K. It is established that the linear temperature dependence of strength, typical of LaB 6 , does not hold in the range 1300–2200 K. It is shown that the theoretical strength increases with higher temperatures. The same dependence is typical of the LaB 6 –MeB 2 systems (Me is Ti, Zr, Hf) at 0.7 mol.% LaB 6 .