Effect of thermomechanical processing on grain boundary character distribution of a Ni-based superalloy

Grain boundary engineering (GBE) was performed on an INCONEL alloy 617 by means of thermomechanical processing (TMP) to optimize the grain boundary character distribution (GBCD) with an increased fraction of low-Sigma coincidence site lattice boundaries (CSLBs). Samples with a 5% thickness reduction followed by annealing at 1100 degrees C for 90 min promoted more low-Sigma CSLBs than those with greater thickness reductions. The fraction of the Sigma 3 '' (Sigma 3, Sigma 9, and Sigma 27) boundaries was promoted preferentially by TMP, which is desirable for the improvement of material's properties. The thermal stability of the GBE-optimized GBCD was verified to be stable at 850 degrees C for 672 It without significant degradation. (c) 2007 Elsevier B.V. All rights reserved.