Growth mechanism of in situ TiB whiskers in spark plasma sintered TiB/Ti metal matrix composites

摘要

In situ TiB whisker reinforced Ti-4.0Fe-7.3Mo matrix composites have been fabricated by spark plasma sintering (SPS). The microstructure of the in situ TiB whiskers and interfacial structures in the composites were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution electron microscopy (HREM). The interfaces between in situ TiB and the Ti matrix are clean and faceted along the ( 100)(TiB) plane. However, small lateral growth steps are observed along the ( 101) and (10 (1) over bar) planes of TiB. Because of the characteristics of the TiB crystal structure, the growing velocity of the ( 100)(TiB) plane along the [ 010](TiB) direction is much faster than that of the [ 001](TiB) direction, which leads to TiB growth as a whisker shape along the [ 010](TiB) direction with a hexagonal transverse section. The growth mechanism of TiB whiskers is a stacking process of the ( 100)(TiB) plane.