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The Microstructure and Distribution of Impurities in Hot‐Pressed and Sintered Silicon Nitrides
Author(s) -
KRIVANEK O. L.,
SHAW T. M.,
THOMAS G.
Publication year - 1979
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1979.tb12737.x
Subject(s) - microanalysis , materials science , microstructure , softening , silicon nitride , silicon , impurity , nitride , intergranular corrosion , scanning electron microscope , interphase , analytical chemistry (journal) , grain boundary , phase (matter) , metallurgy , mineralogy , composite material , chemistry , layer (electronics) , organic chemistry , chromatography , biology , genetics
Two hot‐pressed (HS 130 and NC 132) and two sintered silicon nitrides (with MgO·Al 2 O 3 and Y 2 O 3 additives) were examined in detail by X‐ray diffraction, emission spectroscopy, medium‐and high‐resolution electron microscopy, and X‐ray microanalysis. The overall morphologies of the four materials are quite comparable. Very thin (10 to 20 Å) intergranular glassy films were detected in all the materials at almost all grain and interphase boundaries. The composition of these glasses was determined by X‐ray microanalysis using a 200‐Å electron probe and the softening temperature was estimated from available phase diagrams. The results are in good agreement with the known softening temperatures for the four silicon nitrides, thereby confirming the central role played by glassy phases in determining the high‐temperature mechanical properties of these materials.