Dissociation of Cr-rich M sub(23)C sub(6) carbide in Alloy 617 by severe plastic deformation

In this study, the dissociation of Cr-rich M sub(23)C sub(6) carbides in Alloy 617 was investigated using 50% cold rolling. The major carbides in Alloy 617 consisted primarily of M sub(23)C sub(6) carbide and a small amount of M sub(6)C carbide. The lattice parameters of the carbides were determined as 1.070 nm (M sub(23)C sub(6)) and 1.121 nm (M sub(6)C). The area fraction of the total carbides in Alloy 617 decreased from 3.50% to 1.66% after 50% cold rolling. The M sub(23)C sub(6) carbide was dissociated by the carbon traps in dislocations generated during the severe plastic deformation. Alternatively, the area fraction of M sub(6)C carbide increased from 0.06% to 0.37% during the dissociation of M sub(23)C sub(6) carbide. The area fraction of M sub(6)C carbide increased due to the formation of M sub(6)C carbide as a result of the relative changes in chemical composition, such as Cr and Mo, during the dissociation of M sub(23)C sub(6) carbide.