Experimental evidence of structural evolution for TiB2 microcrystal under externally high stresses

The morphology evolution and defect structure of TiB2 microcrystals treated under high stresses were analyzed using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results show that hexagonal TiB2 with large particle size gradually evolved to flowerlike TiB2 with small particle size under high stresses. The evolution process is mainly determined by the preferential cleavage of TiB2 microcrystal, and the presence of multiple lamellar nanotwin and edge dislocation directly provides some evidence of plastic deformation and structural evolution. For clarity, a possible model is suggested based on the HTREM observation and the natural properties of TiB2 materials to explain the process mechanism.

Graphical abstractThe morphology evolution and defect structure of TiB2 microcrystal treated under high stresses were analyzed using scanning electron microscopy and high-resolution transmission electron microscopy. The results show that lamellar twinned superlattice presents in the samples, accompanied by a few stacking faults near twinned boundary. The interplanar distance for the lamellar nanotwins is about 2.7 nm and the twined planes are oriented along [101¯1] zone axe. The angle between two neighboring twinned wings is about 141o.Figure optionsDownload full-size imageDownload as PowerPoint slide