The change in dispersion of TiB boride formed through the chemical reaction, Ti+CrB&rarrCr+TiB, was investigated in the Ti-Cr system powder compact containing CrB boride particles. EPMA analysis revealed that the shape of the TiB particles was granular type at first, but they began to divide into a large number of fine plate-like TiB particles at the sintering temperature (self-division phenomenon). Although this seems to be contrary to the Ostwald ripening mechanism, the phenomenon could be reasonably explained in terms of total interfacial energy in the system: Considering the grain boundary energy within the granular TiB and the low interfacial energy of coherent plate-like TiB/matrix interface, the total interfacial energy was found to be decreased through the self-division. It was concluded that the difference in the total interfacial energy works as driving force for the self-division phenomenon.
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