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High‐Pressure Sintering of Nanocrystalline γAl 2 O 3
Author(s) -
Mishra Rajiv S.,
Lesher Charles E.,
Mukherjee Amiya K.
Publication year - 1996
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.1151-2916.1996.tb08741.x
Subject(s) - nanocrystalline material , sintering , grain size , materials science , atmospheric temperature range , indentation hardness , mineralogy , high pressure , nanocrystal , metallurgy , analytical chemistry (journal) , microstructure , thermodynamics , nanotechnology , chemistry , chromatography , physics
High‐pressure sintering of nanocrystalline γ‐A1 2 O 3 has been studied over a temperature range of 923‐1323 K and at a pressure of 1 GPa. The γ‐Al 2 O 3 to α‐Al 2 O 3 transformation temperature changed from 1473 K without pressure to ∼1023 K at 1 GPa. Full density was obtained at 1273 and 1323 K in 10 min. The microhardness value of fully dense α‐alumina with a grain size of 142 nm was found to be 25.3 ± 0.8 GPa. The Hall‐Petch slope for the very fine grain size range is different from that of the coarse‐grained alumina.