TITLE:
Scanning Electron Microscopy of Some Slowly Cooled Nickel-Based Hardfacing Alloys Containing Iron Additions
AUTHORS:
J. A. Ajao
KEYWORDS:
hardfacing, alloy, microstructure, precipitation.
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.9 No.2,
February
20,
2010
ABSTRACT: The service lifespan of components used at higher temperatures in corrosive and abrasive
environments can be prolonged by high-temperature corrosion-resistant coatings. This study is
concerned with the microstructural characterization of some slowly cooled Nickel–based
hardfacing alloys investigated by differential thermal analysis (DTA), energy dispersive X – ray
analysis (EDXA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and
transmission electron microscopy (TEM). The alloys were prepared in high frequency induction
furnace under controlled atmosphere. Three major primary hard phases (Ni (α), M7C3, and the
π phase) were identified during slow cooling in DTA depending on the nominal compositions of
the alloys. Large undercoolings as well as intense solid state precipitations were observed in
alloys with iron additions. The precipitations formed the basis of the high hardness values and
strength of the alloys. It was also reported that the hardness values of the alloys increased as the
iron contents increased.