Chemical short-range order in disordered solid solutions often emerges with specific heat treatments. Unlike thermally activated ordering, mechanically derived short-range order (MSRO) in a multi-principal-element Fe₄₀Mn₄₀Cr₁₀Co₁₀ (at%) alloy originates from tensile deformation at 77 K, and its degree/extent can be tailored by adjusting the loading rates under quasistatic conditions. The mechanical response and multi-length-scale characterisation pointed to the minor contribution of MSRO formation to yield strength, mechanical twinning, and deformation-induced displacive transformation. Scanning and high-resolution transmission electron microscopy and the anlaysis of electron diffraction patterns revealed the microstructural features responsible for MSRO and the dependence of the ordering degree/extent on the applied strain rates. Here, we show that underpinned by molecular dynamics, MSRO in the alloys with low stacking-fault energies forms when loaded at 77 K, and these systems that offer different perspectives on the process of strain-induced ordering transition are driven by crystalline lattice defects (dislocations and stacking faults).

Achieving an optimal balance between strength and ductility in advanced engineering materials has long been a challenge for researchers. In the field of material strengthening, most approaches that prevent or impede the motion of dislocations involve ductility reduction. In the present study, we propose a strengthening approach based on spinodal decomposition in which Cu and Al are introduced into a ferrous medium–entropy alloy. The matrix undergoes nanoscale periodic spinodal decomposition via a simple one-step aging procedure. Chemical fluctuations within periodic spinodal decomposed structures induce spinodal hardening, leading to a doubled strengthening effect that surpasses the conventional precipitation strengthening mechanism. Notably, the periodic spinodal decomposed structures effectively overcome strain localization issues, preserving elongation and doubling their mechanical strength. Spinodal decomposition offers high versatility because it can be implemented with minimal elemental addition, making it a promising candidate for enhancing the mechanical properties of various alloy systems.