The Critical Resolved Shear Stress for Twinning in a Modern Single Crystal Ni‐Based Superalloy TMS‐82

Abstract

Detailed observations of the microstructural evolution were performed in single crystal superalloy TMS-82 after thermo-mechanical cycling. An interesting phenomenon shows that the area close to the fracture tends to create a lot of deformation twins, while the area far from the fracture exhibits few deformation twins. Theoretical calculations were further analyzed in an effort to clarify the critical resolved shear stress for twinning in single crystal superalloy by consideration of the special shearing mechanisms of twinning dislocations. The feature that a high density of deformation twins occurs in the area close to the fracture of superalloy TMS-82 due to the stress concentration.

Materials can be strengthened by nanoscale stacking faults

“…Stacking faults (SFs) are one or more layer interruptions in the stacking sequence of a crystal lattice. These interruptions carry a certain amount of SF energy and thus weaken the crystal [1]. Moreover, SFs cause the lattice disregistry in neighboring atomic layers, leading to a natural source of dislocations near them.…”