TITLE:
Microstructure Evolution of a Nickel-Base Alloy Resistant to High Temperature during Aging
AUTHORS:
Alberto Carlos Picasso, César Armando Lanz, Matías Sosa Lissarrague, Aldo Daniel Garófoli
KEYWORDS:
Microstructural Characterization, 35Cr-45Ni Alloy, Aging, Precipitation, Depleted Zones
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.4 No.1,
January
28,
2016
ABSTRACT: In the present study, the microstructural evolution during aging at 1023, 1073, 1123 and 1173 K
of a 35Cr-45Ni heat resistant alloy, produced in the form of centrifugally cast tubes, was characterized
by means of light optical microscopy, scanning electron microscopy (SEM) with secondary
and backscattered electron imaging, energy-dispersive X-ray spectroscopy (EDS) and Vickers
hardness tests. The evolution of the Vickers hardness at 1023 K for aged samples shows that the
microstructure is stable during the analyzed aging period. At 1073 K, the rate of increase in hardness
is lower than 1023 K and this behavior would be associated with morphological changes observed
in primary interdendritic carbides and secondary carbides in the matrix. At 1123 K and
1173 K, an atypical behavior in Vickers hardness curve is presented; where it can be seen that at
certain aging times, the hardness decreases significantly. A microstructural analysis of these samples
indicates that they have a region free of precipitates (near interdendritic edges) where the
hardness is lower. Probably, these regions are areas poor in chromium.