A potential insight into the serration behaviour of Σ3n(n≤3) boundaries in Alloy 617

The serration behavior of Sigma 3(n) (n <= 3) boundaries in Alloy 617 is investigated through electron back scattered diffraction analysis and molecular dynamics (MD) simulation. Furthermore, the implication of grain boundary serrations on the corrosion response in alloy 617 was also evaluated. While Sigma 3 boundaries are never serrated, both Sigma 9 and Sigma 27 boundaries showed mixed serration behavior. Five parameter stereological analysis has revealed that the Sigma 9 and Sigma 27 boundaries lie on both low and high index planes. This observation justifies the mixed serration behavior of Sigma 9 and Sigma 27 considering the fact that boundaries lying on high index planes possess higher surface energy as substantiated through molecular dynamics simulation. Finally, a 'misorientation-deviation' based approach is proposed which could mostly identify those Sigma 9 and Sigma 27 boundaries which are likely to be serrated. The corrosion studies revealed that the serrated specimen is highly resistant to corrosion against the as-received condition.