ISSN 0004-881X

Grain Boundary Evolution in Sm and Nd Sialons during Post-Sintering Heat Treatment

by A. Carman^1*, E.V. Pereloma¹, Y.-B. Cheng²

1) School of Mechanical, Materials and Mechatronics Engineering, University of Wollongong, Australia
2) Department of Materials Engineering, Monash University, Australia

Abstract

Pressureless sintered and hot pressed Sm and Nd sialon ceramics were subjected to post-sintering heat treatments between 1100-1450  for up to 24 hours, and the secondary phase development, grain boundary glass behaviour and a' - B' phase transformation were all studied. The grain boundary phase was found to migrate from the high-energy intergranular film to the grain boundary junctions, and then on to the larger agglomerated pockets of crystalline secondary phase(s) during the heat treatments. The driving force for grain boundary migration was the devitrification and de-wetting of the grain boundary phase at the heat treatment temperatures. Post-sintering heat treatment also resulted in the a' - B' transformation, particularly in the Nd sialon system.

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