Nanocrystalline materials and coatings

S. C. Tjong*, Haydn Chen

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

771 Scopus citations


In recent years, near-nano (submicron) and nanostructured materials have attracted increasingly more attention from the materials community. Nanocrystalline materials are characterized by a microstructural length or grain size of up to about 100 nm. Materials having grain size of ∼0.1 to 0.3 μm are classified as submicron materials. Nanocrystalline materials exhibit various shapes or forms, and possess unique chemical, physical or mechanical properties. When the grain size is below a critical value (∼ 10-20 nm), more than 50 vol.% of atoms is associated with grain boundaries or interfacial boundaries. In this respect, dislocation pile-ups cannot form, and the Hall-Petch relationship for conventional coarse-grained materials is no longer valid. Therefore, grain boundaries play a major role in the deformation of nanocrystalline materials. Nanocrystalline materials exhibit creep and super plasticity at lower temperatures than conventional micro-grained counterparts. Similarly, plastic deformation of nanocrystalline coatings is considered to be associated with grain boundary sliding assisted by grain boundary diffusion or rotation. In this review paper, current developments in fabrication, microstructure, physical and mechanical properties of nanocrystalline materials and coatings will be addressed. Particular attention is paid to the properties of transition metal nitride nanocrystalline films formed by ion beam assisted deposition process.

Original languageEnglish
Pages (from-to)1-88
Number of pages88
JournalMaterials Science and Engineering R: Reports
Issue number1-2
StatePublished - 30 Sep 2004


  • Grain size
  • Ion beam
  • Mechanical properties
  • Nanocrystalline coatings
  • Nanostructure
  • Processing-structure-property
  • Synthesis

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