Phase, microstructure evolution and sintering of Sr-doped TiB2 precursors

Precursors for the preparation of bulk Sr-doped TiB2 composites were synthesized by modified Pechini method. The high temperature behaviour of homogeneous Sr–Ti–B–C–O gels was investigated in the range 1200–1650 °C. DTA-TG analysis of the precursor powder shows two steps of the carbothermal reduction with endothermic peaks at temperatures of 1335 °C and 1500 °C. The influence of strontium content (2, 5, 10, 20 and 50 mol.%) on the phase composition and morphology of powders at 1650 °C was studied.Due to the shift of TiB2 diffractions and the detection of strontium in TiB2 grains by EDX analysis the formation of Ti1 − xSrxB2 solid solution is assumed in the Sr-doped powders. Finally, Sr-doped TiB2 composites were inductive hot-pressed from the as prepared powders at 1900 °C for 7 min. The formation of SrTiO3 phase in the powders is serving as a sintering aid during the preparation of bulk Sr–Ti–B composites. The exaggerated grain growth (grain size up to ∼60 μm) occurs during the sintering with increasing content of strontium in the precursor.