GRAIN-BOUNDARY CHARACTER, AND CARBIDE SIZE AND SPATIAL-DISTRIBUTION IN A TERNARY NICKEL-ALLOY

A preliminary investigation of the grain boundary character and its relationship to carbide distribution in aNi-18Cr-18Fe ternary alloy was conducted. The results showed that there was a strong preference forthe formation of ∑3 (44.6 pct) and twin-related ∑9 and ∑27 CSL boundaries. If the coherent ∑3c twin and the twin-related boundaries are excluded, then the distribution would consist of nearly 80 pct random (high angle) boundaries and about 20 pct CSL (with ∑ ≤ 49) boundaries. The size and spacing of grain boundary carbides were influenced by grain boundary ∑; the carbides being smaller and more closely spaced on the ∑1, ∑9 and ∑27 boundaries, and none could be resolved on the coherent ∑3 twin boundaries. The results could be understood, in part, in terms of the influence of grain boundary energy, but the understanding is incomplete. Further studies are in progress and will be reported. © 1995.