Cooperative and competitive interactions on plastic deformation dynamics in gradient grained dual-phase heterostructures

Abstract

Heterostructured metallic materials hold significant potential for overcoming traditional strength-ductility trade-off, primarily due to their unique hetero-deformation-induced strengthening effects. This study investigates the interplay between competitive and cooperative interactions in strengthening and hardening mechanisms of stainless steel with dual heterogeneity in phase and grain size gradient. Micro-digital image correlation and in-situ electron backscatter diffraction were employed to monitor the evolution of microstructures during deformation, including grain size, phase, and recrystallization state. Additionally, nonlocal spectral crystal plasticity simulations were conducted to quantitatively analyze localized stress-strain and geometrically necessary dislocations distribution. The individual heterogeneity of the grain size gradient plays a cooperative role at the early deformation stage but assumes a competitive role during the intermediate deformation stage, in conjunction with the phase heterogeneity. The dual factors collaboratively dominate the hetero-deformation-induced effect of the integrated sample. This study provides valuable insights into the design of advanced dual/multiple heterostructures.