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Nucleation and Growth of β′‐SiAlON
Author(s) -
Hwang ShyhLung,
Chen IWei
Publication year - 1994
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.1151-2916.1994.tb07042.x
Subject(s) - sialon , nucleation , supersaturation , crystallography , precipitation , materials science , phase (matter) , morphology (biology) , liquid phase , mineralogy , chemistry , metallurgy , thermodynamics , geology , physics , paleontology , ceramic , organic chemistry , meteorology
Elongated β′‐SiAlON grains grown from several finegrained Y m/3 Si 12(m+n) Al m+n O n N 16–r compositions with α‐Si 3 N 4 , AlN, Al 2 O 3 , and Y 2 O 3 starting materials have been examined. These grains have large aspect ratios and are oriented along the [0001] axis. TEM structural and chemical analysis suggests that they are nucleated from various seed crystals, which can be α‐Si 3 N 4 , β‐Si 3 N 4 , or other β′‐SiAlON. The β′‐SiAlON seed and the initial precipitation on β‐Si 3 N 4 show a higher content of Al and O, indicating that a large transient supersaturation of Al and O in the liquid is instrumental for β′‐SiAlON formation, whereas subsequent growth proceeds under a much lower driving force. The misfit between phases is accommodated by interfacial dislocations ( c ‐type and a ‐type). Fully grown β′‐SiAlON grains usually contain several variants independently nucleated from the same seed. In particular, the two alternative α/β phase‐matching possibilities result in two [0001] growth habits separated by a twin boundary.