Element distribution and phase constitution of Al2O3–TiC/W18Cr4V vacuum diffusion bonded joint

Vacuum diffusion bonding between Al2O3–TiC ceramic composites and W18Cr4V tungsten-based tool alloy has been carried out by using Ti/Cu/Ti multi-interlayer. Element distribution near the Al2O3–TiC/W18Cr4V interface was discussed and fracture morphology was analyzed using electron probe microanalysis. Additionally, phase constitutions of the Al2O3–TiC/W18Cr4V joint were determined by X-ray diffraction. The results indicate that Ti-rich layers are formed near both Al2O3–TiC and W18Cr4V. The Ti-rich layer near Al2O3–TiC helps to wet the Al2O3–TiC surface. The Ti-rich layer near W18Cr4V can restrain the formation of Fe–Ti intermetallic compounds in the diffusion transition zone. Residual Cu in the diffusion transition zone can act as a stress releasing zone. The structures of interfacial phases are identified as follows: Al2O3–TiC/TiO + Ti3Al/Cu + CuTi/TiC layer/mixed layer of Fe3W3C, Cr23C6 and α-Fe/W18Cr4V. The fracture morphology of Al2O3–TiC/W18Cr4V joint appears brittle features and the failure occurs within the Al2O3–TiC ceramic.