Microstructure characterisation and mechanical properties of a functionally-graded NbC/high chromium white cast iron composite

Wen Hao Kan, Carlos Albino, Daniel Dias-da-Costa, Kevin Dolman, Timothy Lucey, Xinhu Tang, Li Chang, Gwénaëlle Proust, Julie Cairney

Research output: Contribution to journalArticleResearchpeer-review

17 Citations (Scopus)

Abstract

A functionally graded NbC – high chromium white cast iron composite was successfully fabricated by centrifugal casting for high wear applications. The migration of primary NbC particles to the outer periphery, as predicted by Stokes’ law, resulted in an extremely hard outer layer at the surface of a softer bulk material. Microstructural characterisation showed that both the volume fraction and the morphology of the carbides varies along the thickness of the specimen. At the outer surface, the NbC was present as primary carbides while Chinese-script NbC was found in the bulk of the material. Hardness, sliding wear and three-point bending tests confirmed that the outer layer was harder and more wear resistant than the rest of the material, which was correspondingly tougher. The study of the fracture surface of the specimens showed that there is a strong bond between NbC and the matrix such that delamination between the reinforcements and the matrix did not occur during fracture. If Chinese-script NbC can be reduced or prevented in the bulk material, further improvements to toughness could be achieved.

Original languageEnglish
Pages (from-to)196-205
Number of pages10
JournalMaterials Characterization
Volume136
DOIs
Publication statusPublished - Feb 2018
Externally publishedYes

Keywords

  • Functionally-graded material
  • High chromium white cast iron
  • Metal matrix composite
  • Microstructure
  • Niobium carbide
  • Wear

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