Optimization of alpha-sialon microstructure by heat treatment

Abstract

Nd-doped alpha-SiAlON starting composition (Nd(0.33)Si(9.38)Al(2.62)O(1.62)N(14.38)) was prepared by gas pressure sintering at 1825 degrees C for 3 hrs. In order to explore the effect of post heat treatment on the developments of elongated (alpha-SiAlON grains, sample was heat treated at 1800 degrees C for 4-12 hrs. It was found that post heat treatments promoted formation of the elongated alpha-SiAlON grains. The controlling mechanism of grain growth was determined via plotting on a graph the growth in width/length versus time graphics using Image Analysis method. Different growth rates were found between the length and width direction of the alpha-SiAlON crystals, resulting in anisotropic grain growth in the microstructural development.