A. Osma et al., THE EFFECT OF ELEVATED-TEMPERATURE AND SILICON ADDITION ON A COBALT-BASED WEAR-RESISTANT SUPERALLOY, Journal of Materials Science, 31(17), 1996, pp. 4603-4608
The effects of an elevated temperature and a 5 wt% silicon addition on
the resultant microstructure and inherent phases of Stellite 6 were i
nvestigated by using room and high temperature optical microscopy, X-r
ay diffraction, scanning electron microscopy (SEM) and also bulk hardn
ess and microhardness measurements. It has been observed that exposing
Stellite 6 to heat treatments at 1000 degrees C results in a characte
ristic textured structure and coarsening of interdendritic regions due
to bulk diffusion. In addition, both dendritic and interdendritic har
dness values increase due to texture formation and increased amounts o
f carbide and intermetallic phases, respectively. On the other hand, s
ilicon addition to Stellite 6 causes the transformation of the origina
l spongy dendritic microstructure in as-cast Stellite 6 to a eutectic
dendritic and skeleton interdendritic structure. Also, when silicon ad
ded Stellite 6 was heat treated at 1000 degrees C, particulates emanat
ing from the interdendritic skeleton become irregularly dispersed in t
he dendritic region. In addition, similarly to Stellite 6; a high temp
erature heat treatment results in an increase in hardness values of si
licon added Stellite 6 due to the presence of an Co2Si intermetallic p
hase.