Formation of laminar Ti-Al-N solid solution and interfacial atomistic structure of TiB₂-AlN-B₄C composite

Reactive spark plasma sintering was performed to synthesize TiB₂-AlN-B₄C composite at 1650 °C for 5 min. The results of mechanical tests indicated that the addition of Ti less than 10 wt% is beneficial to its mechanical performances. X-ray diffraction and scanning electron microscope (equipped with energy disperse spectroscopy) reveal the reactions between Ti, B₄C and AlN to form TiB₂ ceramic and laminar Ti-Al-N solid solution that consumes more fracture energy owing to its multilamellar structure and larger aspect ratio. Transmission electron microscope provided an insight into interfacially atomistic structure, surprisingly, two types of diffraction spots were identified as (03¯31)Ti₂AlN and (010)AlN, furthermore, their incoherent interphase boundary composed by atomic facets was illustrated.