Enhanced cryogenic strain hardening in FeCrNi alloy via BCC-particle-induced dislocation walls and deformation twinning

초록

Dislocations in deformed metals often form heterogeneous patterns consisting of alternating regions of high and low dislocation densities, known as dislocation patterning. However, the influence of second-phase particles on dislocation patterns in face-centered cubic (FCC) materials remains not yet fully understood. In this study, the effects of body-centered cubic (BCC) particles on deformation mechanisms and dislocation patterns were investigated using an equiatomic FeCrNi alloy as a model system. The tensile properties and deformation behaviors of the 1200°C-annealed BCC-free material and the 800°C-annealed BCC-containing materials were compared at 293 and 123 K. The single-phase material exhibited wavy dislocation cells (DCs) and planar slip/kink bands. The dual-phase annealed materials developed dislocation walls and DC structures, driven by the facilitated cross-slip of perfect dislocations under high local stresses at the FCC/BCC interfaces. BCC particles enhance cryogenic strength and strain hardening by promoting FCC dislocation walls, increasing internal BCC dislocation density, and activating additional deformation twins. Engineering these particles to control dislocation patterns and plasticity-enhancing mechanisms, including deformation twinning, provides a viable strategy for the microstructural design of advanced cryogenic alloys. © 2026 Elsevier Ltd.

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