Multiple deformed substructures including dislocation cells, nanotwins (NTs) and martensite were introduced in super austenitic stainless steels (SASSs) by cryogenic rolling (Cryo-R, 77 K/22.1 mJ·m⁻²). With the reduction increasing, a low stacking fault energy (SFE) and increased flow stress led to the activation of secondary slip and the occurrence of NTs and martensite nano-laths, while only dislocation tangles were observed under a heavy reduction by cold-rolling (Cold-R, 293 K/49.2 mJ·m⁻²). The multiple precursors not only possess variable deformation stored energy, but also experience competition between recrystallization and reverse transformation during subsequent annealing, thus contributing to the formation of a heterogeneous structure (HS). The HS, which consists of bimodal-grained austenite and retained martensite simultaneously, showed a higher yield strength (~1032 MPa) and a larger tensile elongation (~9.1%) than the annealed coarse-grained Cold-R sample. The superior strength–ductility and strain hardening originate from the synergistic effects of grain refinement, dislocation and hetero-deformation-induced hardening.

A multi-layer accumulative roll bonding (MARB) process was applied to fabricate Al-1 vol% SiC composite (M3) with bimodal structure consisting of 1.07 μm ultrafine grain layers and 0.48 μm finer grain layers. The differences in microstructure, texture and mechanical properties of the M3 samples were systematically compared with conventional MARB-processed Al (M1) and bimodal Al (M2) samples. Optical microscopy (OM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analysis were used to characterize the microstructure evolution of the composites, while the mechanical properties were analyzed by tensile and microhardness tests. As revealed by EBSD results after three cycles, the M3 samples had a bimodal grain structure of 0.48 and 1.07 μm. The texture components of the M3 samples were Brass {011} , S {123} , Cube {001} and Copper {112} . According to SEM observation, ductile fracture of M3 was characterized by acicular dimple and circular micropores. Bimodal Al-SiC composites with high strength (225 MPa) and elongation (13%) were finally synthesized after three cycles. Compared with M1 sheets, the strength and elongation of the M3 sheets increased by 23.2% and 7.4%, respectively, indicating that the M3 samples achieved a synergistic improvement in strength and plasticity.