TiB₂-TiC/1Cr18Ni9Ti and TiB₂-TiC/Ti-6Al-4V graded composites achieved by reaction joining in high-gravity field

1Cr18Ni9Ti and Ti-6Al-4V were selected as the metal substrates, and CrO₃+Al thermit was introduced into B₄C+Ti primary system for adjusting the adiabatic temperature of reaction system as 3 193, 3 282, 3 290 and 3 473 K, TiB₂-TiC/1Cr18Ni9Ti and TiB₂-TiC/Ti-6Al-4V graded composites were prepared by reaction joining in high-gravity field. Because increasing reaction adiabatic temperature brought about the increased melting depth of metal substrates, the intermediate between the ceramic and metal increased in thickness while Al₂O₃ inclusions at the interfacial areas inevitably increased. By changing the processing route, i.e. respectively preparing, ball-milling and compacting B₄C+Ti blends and CrO₃+Al thermit and subsequently filling them one by one into the crucibles, it is found that Al₂O₃ inclusions at the intermediates are removed completely, three-dimensional network ceramic/metal graded composite structure develope in the interface of TiB₂-TiC/1Cr18Ni9Ti, while in the interface of TiB₂-TiC/Ti-6Al-4V there forms the multiscale and multilevel graded composite structure.