Table of Contents
ISRN Thermodynamics
Volume 2012 (2012), Article ID 587584, 7 pages
http://dx.doi.org/10.5402/2012/587584
Research Article

Avoiding or Promoting Graphite in Carbon-Rich Chromium-Containing CoNiFer Cast Alloys—Part 2: Microstructures of the Elaborated Alloys

1Faculty of Sciences and Technologies, University of Lorraine, Boulevard des Aiguillettes, B.P. 70239, 54506 Vandoeuvre-lès-Nancy, France
2Institut Jean Lamour (UMR CNRS 7198), Department of Chemistry and Physics of Solids and Surface, Team 206 “Surface and Interface, Chemical Reactivity of Materials”, Boulevard des Aiguillettes, B.P. 70239, 54506 Vandoeuvre-lès-Nancy, France

Received 14 February 2012; Accepted 19 March 2012

Academic Editors: N. Choudhury and H. Hirao

Copyright © 2012 Ophélie Hestin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Nine M-xCr-yC ternary alloys, three cobalt based, three nickel based and three iron based, were elaborated by foundry, from chemical compositions previously selected by the mean of thermodynamic calculations. They were metallographically characterized, using electron microscopy, image analysis, and X-ray diffraction. The as-cast microstructures are in rather good agreement with the ones predicted at 500 and/or 600°C, despite that the elaboration conditions did not meet any thermodynamic equilibrium criteria. Indeed, the obtained carbides and graphite fractions were close to the calculated ones, and the new chromium contents previously chosen effectively led to the expected microstructure modifications, notably almost total suppression of graphite in the nickel alloys and obtaining large fractions of carbides in the cobalt alloys. This allowed specifying the hardness evolution resulting, for these alloys, from the presence or absence of the soft graphite phase, and from the lowering or the enhancement of the carbides presence.