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Formation of AlN‐Polytypoid Phases during α‐SiAlON Decomposition
Author(s) -
Zhao Rupeng,
Swenser Steven P.,
Cheng YiBing
Publication year - 1997
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.1151-2916.1997.tb03145.x
Subject(s) - sialon , sintering , decomposition , materials science , phase (matter) , transformation (genetics) , work (physics) , chemical engineering , mineralogy , metallurgy , thermodynamics , chemistry , organic chemistry , physics , biochemistry , gene , engineering
Phase transformations from α– to ß–SiAlONs (i.e., from α′ to ß′) have been recently reported in a number of rare‐earth SiAlON systems during postsintering heat treatment. In the present work, this transformation process in a Sm (α+ß)‐SiAlON material is studied by using XRD, TEM, and EDS X‐ray mapping techniques. It is observed that in addition to the formation of ß′ and M′ phases, the α′‐to‐ß′ transformation is accompanied by a significant increase in the amount of an AlN‐polytypoid phase. The results suggest that some α′ phases are thermodynamically unstable at temperatures lower than the material sintering temperature and will decompose when conditions allow. For the composition studied in this work, the α‐SiAlON decomposition can be described in general as α′→ß′+ M′+ AlN polytypoid.