TiCの表面析出機構

抄録

Our previous work on Ti containing alloys shows that TiC precipitated at the alloy surfaces acts as an adhesive between the ceramics and the alloy. It is important, therefore, to elucidate the mechanism of the TiC surface precipitation on the alloys. It is noted that precipitation of small TiC particles in alloy matrices produces the interfacial and strain energy at the interface, and the extra energy from these sources appears to be responsible for the precipitation of these TiC particles to the surface. This work shows that small TiC particles are present in the matrix of these Ti contain ing alloys throughout the temperature region in which the extensive surface precipitation of TiC is observed, although according to an available phase diagram the TiC precipitate is absent in the matrix of these alloys. If the surface TiC originates from TiC in the matrix, the TiC surface precipitation rate must increase with increasing diffusivity of Ti and C in the matrix. This diffusivity effect was experimentally confirmed. These results are in accord with the presumption that the driving force for the surface precipitation is the interfacial and strain energy.