Sample size induced brittle-to-ductile transition of single-crystal aluminum nitride

J. J. Guo, K. Madhav Reddy, A. Hirata, T. Fujita, G. A. Gazonas, J. W. McCauley, M. W. Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


Ceramics are known to be mechanically hard, chemically inert and electrically insulating for many important applications. However, they usually suffer from brittleness and have moderate strength that strongly depends on their microscopic structure. In this study, we report a size induced brittle-to-ductile transition in single-crystal aluminum nitride (AlN). When the specimen diameters are smaller than ∼3-4 μm, AlN micropillars show metal-like plastic flow under room-temperature uniaxial compression. The unprecedented plastic strain of ∼5-10% together with the ultrahigh strength of ∼6.7 GPa has never been achieved before. Transmission electron microscopy demonstrates that dislocations play a dominant role in the plasticity of the micro-sized AlN.

Original languageEnglish
Pages (from-to)252-259
Number of pages8
JournalActa Materialia
Publication statusPublished - 2015 Apr 15
Externally publishedYes


  • Ceramics
  • Micropillar
  • Plastic deformation
  • Size effect
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys


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