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Processing and Properties of in Situ ‐Reinforced α‐SiAlONs Stabilized with Y 2 O 3 and Lu 2 O 3
Author(s) -
Jones Mark I.,
Hyuga Hideki,
Hirao Kiyoshi,
Yamauchi Yukihiko
Publication year - 2004
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.1551-2916.2004.00710.x
Subject(s) - equiaxed crystals , materials science , microstructure , grain boundary , grain growth , fracture toughness , phase (matter) , grain size , mineralogy , analytical chemistry (journal) , composite material , crystallography , metallurgy , chemistry , organic chemistry , chromatography
α‐SiAlONs with equiaxed and elongated microstructures stabilized with Y 2 O 3 and Lu 2 O 3 were produced by hot pressing, and the phase structure and room‐ and high‐temperature mechanical properties were assessed. Additional liquid added to the starting composition in the form of 5 wt% rare‐earth monosilicate resulted in the formation of elongated microstructures and improvements in room‐temperature strength and fracture toughness. The elongated grain growth was promoted by the additional liquid phase, which crystallized to form a secondary grain‐boundary phase thought to be J ′ (Re 4 Si 2– x Al x O 7+ x N 2– x ). For the equiaxed and the elongated samples, those sintered with Lu 2 O 3 showed higher hardness than the comparable Y 2 O 3 ‐sintered materials, and, at elevated temperature, the strength retention of the elongated Lu 2 O 3 SiAlON was much higher than that of the Y 2 O 3 sample, which was attributed to properties of the residual grain‐boundary phase associated with the difference in the cationic radius of the stabilizing cation.