| 摘 要： | Ca α -Sialon compacts pressurelessly-sintered to the intermediate temperature (1 450℃) were investigated with TEM for an overall composition Ca1.8Si6.6Al5.4O1.8N14.2. It was found that in most cases, the newly-formed α -Sialon grains had no epitaxial orientation relationship with the Si3N4 particles; only occasionally heteroepitaxial nucleation of α -Sialon on α -Si3N4 was detected. Further EDAX analysis revealed a much higher Ca concentration in the non-epi- taxially nucleated α -Sialon than in the heteroepitaxially nucleated α -Sialon. Thus a possible correlation between the concentration of metal cations in the α -Sialon structure and the nucleation mechanism has been proposed, i.e. α -Sialon compositions with higher Ca concentration show a stronger trend of non-epitaxial nucleation.
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