Lattice Rotation and Deformation Mechanisms under Tensile Loading in a Single-Crystal Superalloy with [001] Misorientation

TL;DR

This study explores how slight deviations from the [001] crystal orientation affect the strength and deformation behavior of a nickel-based single-crystal superalloy under tensile loading.

Contribution

The paper identifies how lattice rotation and slip mechanisms change with deviation angles, linking them to differences in strength and ductility.

Findings

Strength decreases and ductility increases with larger deviation angles from [001].

At lower angles, short lattice rotation paths and work hardening cause superlattice stacking faults.

At higher angles, extended lattice rotation paths and Shockley partial dislocations in γ channels increase ductility.

Abstract

This study investigates how deviation angles close to the [001] orientation affect the tensile properties and deformation behavior of a nickel-based single-crystal superalloy at room temperature. The research focuses on samples with deviation angles of 3°, 8°, and 13° from the [001] orientation and examines their strength and ductility. We employed scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) to explore the deformation micro-mechanisms at varying angles. Findings reveal that strength decreases and ductility increases as the deviation angle widens within the [001] vicinity. The study emphasizes that <110> octahedral slip-driven crystal slip and rotation are crucial for understanding tensile deformation. The deformation differences in samples at varying angles are attributed to the differential engagement of mechanisms. Specifically, at lower angles, reduced ductility and increased strength are due to short lattice rotation paths and work hardening causing superlattice stacking faults (SSFs) to slip in two directions on the {111} plane within the γ′ phase. As the angles increase, the lattice rotation paths extend, and Shockley partial dislocations (a/6<112>) accumulate in γ channels. This process, involving SSFs moving in a single direction within the γ′ phase, results in higher ductility and reduced strength.

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