Dmytro Demirskyi

Consolidation of B4C-TaB2 eutectic composites by spark plasma sintering

Abstract The in situ synthesis/consolidation of B4C-TaB2 eutectic composites by spark plasma sintering (SPS) is reported. The microstructure–property relations were determined for composites with the B4C-TaB2 eutectic composition as functions of TaB2 content, and TaB2-TaB2 interlamellar spacing. A clear maximum in fracture toughness was identified (∼4.5 MPa m1/2) for eutectic composites with interlamellar spacing between 0.9 and 1.1 μm. The composites with the hypereutectic composition of 40 mol.% TaB2 obtained by SPS exhibited lower Vickers hardness (25–26 GPa) but higher indentation fracture toughness (up to 4.9 MPa m1/2) than eutectic composites with 30–35 mol.% of TaB2.

Grain Growth Kinetics During Microwave Sintering of the Nanocrystalline Titanium Nitride

Microstructural evolution and grain growth kinetics of nanocrystalline titanium nitride powders were investigated, when being isothermally annealed using microwave and conventional sintering. The results show that, microwave sintering of nanocrystalline TiN results in fine microstructure ~220 nm, as compared to the conventional sintering 335 nm. Grain growth process during microwave sintering occurred mainly by mechanism of grain-boundary diffusion with an activation energy of 230 kJ mol−1, while in case of conventional sintering, the mechanism of volume diffusion was assumed with the activation energy of 390 kJ mol−1.