Abstract
Analytical transmission electron microscopy (ATEM) was
used to examine the effect of post-irradiation annealing
(PIA) on radiation-induced segregation (RIS) at the grain
boundaries of 7.7 dpa AISI 304 stainless steel. The grain
boundary profiles and the irradiation damage were
analysed in the as-irradiated state and after PIA of 6
hours at 500 °C and after 25 hours at 500°C and 550°C by
using transmission electron microscopy (TEM). As a main
conclusion from the TEM examinations, the effects of PIA
were found to be relatively small after only 6 hours,
while after 25 hours of PIA at both 500 and 550°C, RIS
was almost recovered and only marginal deviation in
chemical composition could be found near the GB. The
as-irradiated state showed extreme RIS values of Si 4.9
wt%, Cr 14.7 wt%, Ni 23.4 wt%, and P 1.4 wt%., while upon
PIA for 6 hours the extreme values for RIS were Si 3.9
wt%, Cr 16.0 wt%, Ni 21 wt%, and P 0.9 wt%. After 6 hours
annealing at 500°C dislocation loops start to grow, while
dislocation density remains of the same order of
magnitude. After annealing for 25 hours at 500°C the
average size of dislocation loops remains nearly the
same, while dislocation density was reduced almost by one
fold. In the areas where dislocation density was found to
be the lowest some features, which can most likely be
attributed to stacking fault tetrahedral (SFT) were
found. Annealing at even higher temperature (550°C)
affected the average size of the dislocation loops,
making them almost twice as large as well as resulting in
a very broad distribution of dislocation sizes. Density
of dislocations is also reduced by one fold in comparison
to the as irradiated condition and leads to formation of
SFT's, which could be consistently found in the specimen.
None of the applied PIA treatments had caused formation
of voids.
Original language | English |
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Title of host publication | Fontevraud 8 |
Subtitle of host publication | Conference on Contribution of Materials Investigations and Operating Experience to LWRs' Safety, Performance and Reliability |
Number of pages | 11 |
Publication status | Published - 2014 |
MoE publication type | A4 Article in a conference publication |
Event | Fontevraud 8: Conference on Contribution of Materials Investigations and Operating Experience to LWRs' Safety, Performance and Reliability - Avignon, France Duration: 15 Sept 2014 → 18 Sept 2014 |
Conference
Conference | Fontevraud 8 |
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Country/Territory | France |
City | Avignon |
Period | 15/09/14 → 18/09/14 |
Keywords
- transmission electron microscopy
- radiation induced segregation
- post irradiation annealing