Anisotropic grain growth of R-α-sialon (R = Nd and Er)

摘要

Two R-α-sialon (R0.6Si9.3Al2.7O0.9N15.1, R=Nd and Er) compositions were first fired at 1750°C/25 min and 1650°C/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°C 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.