Two R-α-sialon (R_(0.6)Si_(9.3)Al_(2.7)O_(0.9)N_(15.1), R=Nd and Er) compositions were first fired at 1750℃/25 min and 1650℃/2 h respectively for completion of the α→α′ phase transformation. Elongated α-sialon grain morphology was developed in both samples after being re-fired at 1800℃ for different periods of time. The growth in width of R-α-sialon grains is controlled by diffusion in the liquid, while the length growth tends to be interfacial reaction controlled. The anisotropic growth of R-α-sialon is attributed to the large difference in the growth rate constant between the length and the width directions of the grain.
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