Implication of grain boundary engineering on high temperature hot corrosion of alloy 617

The role of grain boundary engineering (GBE) on high-temperature hot corrosion behavior of alloy 617 was evaluated by exposing both the as-received (AR) and GBE specimens in a salt-mixture of (75% Na2SO4 + 20% NaCl + 5% V2O5) at 1273 K for 24 h. The AR specimen having continuous network of random high angle grain boundaries (HAGBs) has undergone hot corrosion and substantial depletion/segregation of alloying elements through the entire cross section. The GBE specimen exhibited significantly reduced hot corrosion and depletion/segregation of alloying elements. This is attributed to the high fraction of 3-CSL triple junctions which break the percolation in the random HAGBs network.