Growth mechanism of primary needles during the solidification of chromium carbide overlays

Nairn Barnes, Samuel Clark, Sridhar Seetharaman, Patricio F. Mendez

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

A mechanism for modelling the growth of faceted primary M7C3 needles during solidification of chromium carbide overlays is presented for the first time. In contrast with existing models that consider diffusion-controlled growth over the length of the needle, this work disaggregates the flow of solute at the tip (diffusion-controlled) and the faceted sides (interface-controlled). The proposed solution predicts an initial transient followed by a steady state longitudinal growth. The outward growth of the needle prism faces is linear and slow, consistent with interface-dominated kinetics. Abrupt decreases in longitudinal growth rate was observed when the tip of the carbides approached other carbides, consistent a soft-impingement effect when the diffusion field of two carbides a overlap. The model was compared to in-situ visualisation of the solidification of an alloy with primary chromium carbide needles, and was found to match closely to observations.

Original languageEnglish (US)
Pages (from-to)356-365
Number of pages10
JournalActa Materialia
Volume151
DOIs
StatePublished - Jun 1 2018
Externally publishedYes

Keywords

  • Chromium carbide overlays
  • Diffusion-controlled growth
  • Faceted needle growth
  • MC

ASJC Scopus subject areas

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

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