ORNL-4191 - the Molten Salt Energy Technologies Web Site

Figure 18.20 shows an area near the edge of the
sample, where grain boundaries contain a telluriumrich
phase. Electron microprobe examination oE
this region confirmed the presence of tellurium and
indicated that it was preferentially associated with
the large carbide precipitates within grain boundaries.
The penetration of the tellurium into the alloy
was only about 0.005 in. following the 1832°F
heat treatment. No penetration was found for
samples heat treated at 1472 or 1652'F.
Elemental scans of the microprobe within the
tellurium phase shown in Fig. 18.19 indicated
235
that manganese and chromium were also present.
These elements were preferentially segregated
into bands within the tellurium matrix and undoubtedly
resulted from the leaching of these elements
from the Hastelloy N during the 1832°F
heat tree tments.
The results of these tests indicate that liquid
and/or vaporized tellurium metal interacts with
Hastelloy N to a minor extent under the conditions
tested, which included up to 150 kr in contact at
1832'F. No reduction in room-temperature or
elevated-temperature ductility was found. These
tests will be extended to longer exposure times.