In situ growth of elongated alpha-sialon grains in Li-alpha-sialon ceramics

In situ growth of elongated alpha -sialon grains has been studied in Li-alp ha -sialon ceramics. The morphology of alpha -sialon grains is mainly deter mined by the overall composition, with low m and high n values promoting th e anisotropic grain growth of alpha -sialon needles with even more pronounc ed effects at higher sintering temperatures and pressures. beta -Si3N4 star ting powder can also facilitate the growth of elongated alpha -sialon grain s since it reduces the number of sites where alpha -sialon grains can nucle ate. The effects of processing parameters on the growth of elongated alpha -sialon grains were examined. For single-phase alpha -sialon starting compo sitions, increases in sintering time do not promote the elongated (or even equiaxed) growth of alpha -sialon grains after the formation of alpha -sial on is complete. (C) 2001 Elsevier Science Ltd. All rights reserved.