Thermal dependent properties of LaB6–MeB2 eutectic composites

The thermal expansion of polycrystalline LaB6–MeB2 ceramic composites (where Me denotes Ti, Zr, Hf) has been studied experimentally within the temperature range from 20 °C to 1500 °C. These were obtained by crucible-free float zone melting method. first interval with a negative elongation (NTE) (~1000–1100 °C) coincided in and LaB6 hexaboride was associated La–La atomic bond softening. hierarchy interatomic Me–Me–B–B bonds composite compounds, their interface residual stresses matrix MeB2 reinforcing phase identified be source such phenomenon. strong covalent component compresses crystal lattice after softening ionic metallic components removing stresses. exhibited several additional NTE intervals at higher (~1000–1250°?) which TiB2, HfB2, ZrB2 fibers. determines transition deformation mechanism low-temperature high-temperature one. Insignificant plasticity brittle fracture area is replaced an increase both strength rise.