Microstructural characterization of TiB in in situ synthesized titanium matrix composites prepared by common casting technique

Titanium matrix composites reinforced with TiB and TiC were fabricated by a non-consumable arc-melting technology utilizing self-propagation high-temperature synthesis reaction between titanium and B4C. Microstructural characterization of in situ synthesized TiB was observed by scanning electron microscope (SEM), transmission electron microscope (TEM) and high-resolution transmission electron microscope (HREM). The TiB shows a typical whisker shape and the crystallographic planes of the TiB at transverse cross-section are always of the planes (100), (101) and (10 (1) over bar). Stacking faults are observed in the TiB. The TiB forms in a way of nucleation and growth. The growth morphologies and formation of the stacking faults are related to crystal structure of the TiB. Due to its B27 structure, the TiB is likely to grow along [010] direction and form the whisker shape. The stacking faults are also likely to form in the (100) plane. The formation of above morphologies and the stacking faults serves to minimize the lattice strain at the interface between the TiB and the titanium matrix alloy. (C) 2001 Elsevier Science BY. All rights reserved.