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Perfect High‐Temperature Plasticity Realized in Multiwalled Carbon Nanotube‐Concentrated α‐ Al 2 O 3 Hybrid
Author(s) -
Estili Mehdi,
Sakka Yoshio,
Wu WenWen,
Nishimura Toshiyuki,
Yoshida Hidehiro,
Kawasaki Akira
Publication year - 2013
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/jace.12332
Subject(s) - materials science , ceramic , nanostructure , composite material , plasticity , equiaxed crystals , strain hardening exponent , nanotube , deformation (meteorology) , nanotechnology , carbon nanotube , microstructure
We investigate the high‐temperature compressive deformation behavior of a novel, fully dense and structurally uniform, 20 vol% multiwalled carbon nanotube ( MWCNT )–α‐ Al 2 O 3 matrix hybrid, which has a strong room‐temperature interfacial shear resistance ( ISR ) and a unique MWCNT ‐concentrated grain‐boundary ( GB ) structure. We realized a perfect plastic deformation at 1400°C and a rather high initial strain rate of 10 −4 s −1 by a low ~30 MPa flow stress, which is contrary to the strain hardening response of fine‐grain monolithic Al 2 O 3 . This unique performance in CNT –ceramic system in compression is explained as follows: the concentrated network of individual MWCNT s perfectly withstands the high‐temperature and shear/compressive forces, and strongly preserves the nanostructure of Al 2 O 3 matrix by preventing the dynamic grain growth, even during a large ~44% deformation. Furthermore, the presence of large amount of radially soft/elastic, highly energy‐absorbing MWCNT s in the GB and specially multiple junction areas, and a potentially weak 1400°C‐ ISR , could greatly facilitate the GB sliding process (despite the hybrid's strong room‐temperature ISR ), as evidenced by the formation of some submicrometer‐scale MWCNT aggregates in GB area, the equiaxed grains and dislocation‐free nanostructure of the deformed hybrid. The results presented here could be attractive for the ceramic forming industry and could be regarded as a reference for oxide systems in which, the GB areas are occupied with soft/elastic, highly energy‐absorbing nanostructures.