Medium-entropy alloys (MEAs) with face-centered cubic (FCC) structure generally possess exceptional ductility, however, their relatively insufficient strength and high raw material costs significantly constrains practical industrial application. In this work, high-density deformation twins are introduced into a cost-effective (Fe40Mn40Cr10Ni10)96.6C3Ti0.4 (at%) MEA by performing cryogenic rolling (cryo-rolling) and low-temperature annealing, resulting in an optimized strength-ductility synergy. The (Fe40Mn40Cr10Ni10)96.6C3Ti0.4 MEA processed by cryo-rolling and annealing at 500 degrees C for 2 h maintains an unrecrystallized FCC matrix, while encompassing lots of dislocations, nano-scale carbides, nano-twins and microbands. This MEA demonstrates outstanding mechanical properties with yield and ultimate tensile strength of 1256 MPa and 1329 MPa at 298 K and 1682 MPa and 1802 MPa at 77 K, respectively, with concurrently maintained ductility above 10 %. The exceptional strength stems from dislocation, grain boundary, precipitation and twin boundary strengthening. Furthermore, the deformation mechanism transitions from dislocation mobility at 298 K to coordinated dislocation slip and deformation twinning at 77 K. With a raw material cost of $4.25/kg, the developed MEA exhibits superior cost-effectiveness and high-performance compared to most of H/MEAs. The study provides valuable insights for developing cost-effective and high-performance H/MEA.

To achieve a synergistic combination of high strength and ductility in titanium alloys at 700 degrees C, a novel near-alpha high temperature titanium alloy Ti-5.8Al-4.0Sn-4.0Zr-0.31Nb-0.62Ta-1.26W-0.4Si was designed. The microstructure was subsequently optimized through hot forging followed by heat treatment, and its microstructural evolution was systematically investigated. Results indicated that with increasing solution temperature from 950 degrees C to 1050 degrees C, the volume fraction of primary equiaxed alpha phase (alpha p) decreased while the transformed beta phase (beta t) and secondary lamellar alpha phase (alpha s) increased. The microstructure evolved from predominantly equiaxed alpha to a lamellar structure. Tensile tests conducted at 700 degrees C revealed that the samples solution-treated in the upper half of the alpha+beta region (1000 degrees C) exhibited the superior combination of strength and ductility, achieving a tensile strength of 576.2 MPa while maintaining an elongation of 22.3%. The superior mechanical properties can be attributed to the refined alpha p and beta t phases. The dislocation motion is hindered by fine alpha s lamellae while interfacial pinning effects combined with an oriented arrangement of dispersed S2 silicide precipitates contribute to synergistic strengthening.

Heavy carbon doping is an effective strategy to enhance the mechanical properties of face-centered cubic (FCC) medium/high-entropy alloys (M/HEAs), but often induces ductile-brittle transition (DBT) at cryogenic temperatures, restricting their cryogenic applications. Herein, the (Fe40Mn40Co10Cr10)96.7C3.3 MEA was prepared and cold rolled at room temperature to pre-introduce deformation into microstructure to avoid the cryogenic DBT behavior. Furthermore, the effects of cold rolling reduction and temperature on the mechanical response, deformation mechanisms and fracture characteristics were systematically investigated. The results show that the MEA maintains a single FCC phase without phase transformation during cold rolling and subsequent tensile deformation. At 298K, the alloy exhibits a typical strength-ductility trade-off, i.e., yield strength increases linearly from 476MPa to 1279MPa, while fracture elongation decreases from 70.1% to 12.6%, accompanied by a fracture mode transition from shear to normal fracture with increasing cold rolling reduction. In contrast, at 77K, the alloy manifests a non-monotonic ductility evolution, that is, fracture elongation first decreases to 12.7% at 20% rolling reduction but rises to 26.5% at 30% rolling reduction, achieving superior strength-ductility synergy (yield strength: 1625MPa), which is attributed to the extensive activation of deformation twins that not only accommodate plastic strain, but also suppress strain localization, effectively transforming the fracture mode from intergranular to transgranular fracture. Quantitative analysis of strengthening mechanisms reveals that dislocation strengthening and twin boundary strengthening are the dominant contributors to yield strength. This work demonstrates that opportune pre-deformation is an effective approach to tailor the deformation mechanisms and inhibit cryogenic brittleness for carbon doped M/HEAs.

Optimizing strength-ductility synergy is a key challenge for advanced casting high/medium entropy alloys (H/MEAs). In this study, the microstructure and mechanical properties of (AlCrFe2)65Ni35 vermicular eutectic MEA were studied by doping Si (0–3 at.%). Si addition promoted a partial shift from vermicular to lamellar eutectic morphology in the MEA. The Ni34Fe32Cr16Al16Si2 MEA achieves a yield strength of 960 MPa, tensile strength of 1300 MPa, and ductility of 8.8%, outperforming most cast eutectic H/MEAs. This results from combined Si-induced solid-solution hardening, increased BCC phase volume fraction, and hetero-deformation-induced (HDI) hardening.

Developing an alloy with mechanical stability across a wide temperature range, excellent mechanical properties and low cost has great engineering significance, but achieving this synergy in a single alloy remains highly challenging. This study proposes an innovative design method for advanced medium-entropy alloys (MEAs), and successfully synthesizes a low-cost (Fe44Ni30Cr15Al7Ti2Si2)99.6Zr0.1B0.1C0.2 MEA. This MEA has exceptionally temperature-insensitive mechanical properties between 77 K and 973 K, retaining high yield strength (~760 MPa at 298 K, ~870 MPa at 77 K, ~620 MPa at 973 K) and ductility over 25% at all tested temperatures. This performance exceeds almost all reported alloys, including those with high Co/Ni content, enabled by the synergy of nanoscale L12 precipitates, short-range order, dislocations, slip bands, stacking faults and twin boundaries. This highlights the potential of Fe-based MEAs for key applications in aerospace, automotive and energy sectors, meeting the performance requirements of modern industries under dynamic environment conditions.

The electrochemical migration (ECM) failure behavior of Ag electrodes under single-phase square-wave AC loading was investigated using the thin electrolyte film method, and a mechanistic model was established to elucidate the influence of frequency on ECM. From 100 to 106 Hz, the failure mode varied from a dendrite-induced short-circuit failure, to a probably precipitate-induced creepage failure without any dendrite occurred. As frequency increases, a large number of ions retained and deposited in the migration pathway, thereby suppressed dendrite formation. The simulation results of the model are in good agreement with the experimental results, revealing a new mechanism for ECM failure.

A functional composite coating system was developed on VW75 magnesium alloy to address the trade-off between corrosion resistance and electrical conductivity. A micro-arc oxidation (MAO) inner layer incorporating Ta2O5 particles was first fabricated, followed by the deposition of an epoxy resin topcoat doped with PEDOT: PSS and cobalt (Co) powder. The microstructure, phase composition, and electrochemical properties of the composite coatings were systematically characterized. The results indicated that the incorporation of Ta2O5 particles significantly enhanced the compactness of the MAO layer, with optimal corrosion resistance achieved at a Ta2O5 concentration of 6 g/L. When the concentration of Ta2O5 is 6 g/L, the pore size distribution of the coating is moderate, which can form a strong bonding force with the epoxy coating. The subsequent application of the modified epoxy topcoat further augmented the protective performance via a pore-sealing effect. Notably, the corrosion resistance was positively correlated with the content of dopants. Furthermore, the PEDOT: PSS and Co fillers facilitated the formation of a conductive percolation network within the epoxy matrix, thereby imparting excellent electrical conductivity to the composite. These findings demonstrate the potential of this dual-layer coating strategy for protecting magnesium alloys in harsh marine environments.

The heterogeneous structure has shown promising potential in tailoring the mechanical properties of ferrous medium entropy alloys (Fe-MEAs). However, regarding its practical application, the influence of the heterogeneous structure on the corrosion behavior must also be considered. In this study, the corrosion behavior of a (Fe65Ni15Co10Cr10)92Ti5Al3 (at.%) MEAs with a dual heterogeneous structure was investigated in 3.5 wt% NaCl solution. The dual heterogeneous structure comprises a partially recrystallized matrix and heterogeneously distributed nanoprecipitates. The results presented herein indicate that tuning the heterogeneous structure does not worsen the corrosion resistance of the (Fe65Ni15Co10Cr10)92Ti5Al3 MEA. A detailed analysis reveals that this excellent corrosion resistance can be attributed to an enhanced ability for passive layer formation and stability. The dual heterogeneous structure contributes to higher densities of dislocations, grain boundaries, phase boundaries, and L12 phase within the specimens, thereby facilitating passive layer formation. Furthermore, the stability of passive layer is associated with high-valent oxides such as Cr2O3 and TiO2. Consequently, the remarkable corrosion resistance exhibited by (Fe65Ni15Co10Cr10)92Ti5Al3 MEA with a heterogeneous structure arise from synergistic effects arising from both its high the formation capability and stability of the passive layer.

The corrosion behavior of CoCrNi MEA in a mixed HF and HCl medium was investigated by immersion tests. The alloy exhibits superior corrosion resistance compared to Ni-based alloys, including enhanced passivation capability and insensitive to temperature variations. The underlying mechanisms are closely associated with the protective barrier provided by the Cr and Co oxide films that form during corrosion, attributed to their higher work function and lower binding energy. Co element shortens bond length between adsorbate and surface atoms, enhancing adsorption of the adsorbate on both Cr and Ni, which promotes stable oxide layer formation.

In this study, the deformation behavior of TiZrHf MEA at the temperatures ranging from 273 K to 673 K was experimentally investigated. The results demonstrated that alloy exhibits excellent comprehensive mechanical properties within this temperature range, particularly highlighting a remarkable work hardening capability during high temperature deformation. Microstructure analysis revealed that the double cross-slip of and dislocations predominantly govern room temperature deformation of the alloy. In contrast, high temperature deformation is primarily influenced by cross-slip, twinning and dynamic strain aging. The pronounced work hardening ability observed in the alloy during high temperature deformation can be attributed to the synergistic effects of cross-slip, twinning and dynamic strain aging induced by significant lattice distortion within the microstructure.

The development of cost-effective, strong, and ductile alloys for various temperatures is crucial but challenging for the modern industry. In this study, we designed a series of novel L12-strengthened (Fe58.98Ni31.7Al6Ti3Zr0.1C0.2B0.02)100−xCrx (x = 0, 4, 8, and 13 at

Polyimide aerogels as thermal protective materials highly support the safety of aerospace vehicles in resisting relative high temperature caused from aerodynamic heating. However, their service life and durability prediction remain poorly understood, leading to a challenge for interplay regulation between nano-structure and macroscopic property in natural environment. Here, we show performance evolution pattern and microstructural mechanism for polyimide aerogels abundant in robust chemical linkages during 165-day service period exposure to natural weathering. There has been partial amplitude degradation for compressive characteristic, thermally insulating, dimensional shrinkage, and hydrophobicity, which greatly happened at the initial stage of 15−30 days. This phenomenon is caused by finer of nano-networking skeletons and smaller of porous structures in subjecting natural conditions from a microscopic perspective, further demonstrating the weakening and breaking occurrence of ether bonds and imide rings susceptible to environmental impact. Cycling and durability tests suggest the extension of service life could be modulated by strengthening chemical linkages and structural rings, especially in improving the tolerance and robustness of the aerogels at the beginning of service. These findings provide an innovative understanding for the life-cycle behavior of high-performance polyimide aerogels in aerospace, offering critical design approach for long-term weatherability and the service life prediction of polymer aerogels in natural environment.

We study the mild Skorohod solution to the following fractional stochastic heat equation on ℝ: ∂_t u(t,x)=-(-Δ)^ρ/2 u(t,x) +βu(t,x)δ_0(x)ξ(t), u(0,·)=u_0(x), where -(-Δ)^ρ/2 with ρ∈(0,2] is the fractional Laplacian and ξ is a Gaussian noise with covariance 𝔼[ξ(t) ξ(s)]=|t-s|^2H-2 for H∈(1/2, 1]. This equation with ρ∈(1,2] arises naturally in the study of the disordered pinning model. We show that the equation admits a local L^2-solution when ρ= 2, whereas, for ρ∈ (0,2), any solution–if it exists uniquely–cannot be L^p-integrable for any p > 1. Moreover, inspired by the recent work of Quastel, Ramirez and Virág, we prove that the equation has a unique global L^1-solution whenever 1/ρ+1<2H. We also establish the strict positivity of the solution. Our work partially fills the gap in the study of the Weinrib-Halperin prediction.

The dependence of deformation-induced martensitic transformation (DIMT) kinetics on mechanical response and fracture behavior of metastable Fe-based medium-entropy alloys (Fe-MEA) remains unclear. In this work, Fe67-xCr13Ni10Si7Al3Cox (x=5, 8 and 10 at.%) MEAs were prepared by substituting Co for Fe to tune FCC stability and FCC to BCC transformation kinetics. Increasing Co content from 5 at.% to 10 at.% raises the valence electron concentration from 7.56 to 7.61 and increases the initial FCC fraction from 65.2% to 77.1%, indicating progressive FCC stabilization. At 298 K, Co substitution improves the yield strength from 963 to 1120 MPa and the elongation from 37.5% to 48.8%, because the BCC products remain ductile and can deform synergistically with the FCC phase matrix despite weakened transformation kinetics. By contrast, at 77 K, the yield strength increases from 1300 to 1415 MPa, but the ultimate tensile strength and elongation decrease from 1982 to 1461 MPa and from 29.9% to 15.6%, respectively. The main reason is that higher Co content generates fine and isolated BCC products during DIMT, which exhibit almost no plastic deformation capability and cleave to trigger microcrack in subsequent deformation process, resulting in premature fracture at 77 K. These results demonstrate that the mechanical response and fracture resistance of metastable Fe-MEAs is dominated by DIMT kinetics, martensite morphology and the temperature-dependent mechanical property of BCC products.

We designed and fabricated a novel Fe-rich Co-free Fe2CrNiCu0.5Si0.2Ti0.1 high-entropy alloy (HEA) with ultrahigh-strength and anti-bacterial potential. It exhibits a face-centered-cubic (FCC) matrix with three types of well-dispersed nanoscale precipitates: Cu-rich FCC, Cr-rich body-centered-cubic (BCC), and (Ni,Ti,Si)-rich B2 phases, as well as high-density dislocation. Such complex microstructure leads to exceptional mechanical and anti-bacterial synergy, including a yield strength of similar to 1.26GPa, ultimate tensile strength of similar to 1.45GPa with certain tensile plasticity, while achieving a > 99.99% anti-bacterial rate against E. coli. This work provides a novel strategy for designing cost-effective HEAs with ultra-high strength and superior anti-bacterial performance, as well as valuable insights for developing advanced multi-functional metallic materials.

Developing high strength, high ductility and corrosion resistant high- and medium-entropy alloys (H/MEAs) is a current research hotspot, which is primarily sourced from Ni/Co-rich H/MEAs and expensive. In this study, cost-effective (Fe62Co8Ni15Cr15)(100-x)Mo-x (x = 0, 2, and 3 at.%) Fe-based MEAs were designed. The experimental results show that Mo doping leads to a better strength-ductility balance and improves the corrosion resistance. The (Fe62Co8Ni15Cr15)(97)Mo-3 MEA shows excellent mechanical properties (600 MPa yield strength and 26% uniform elongation at 298 K; 990 MPa and 42% at 77 K) and corrosion-resistance (pitting potential similar to 0.83V in 3.5 wt% NaCl solution), outperforming 316L stainless steel and several corrosion-resistant Ni/Co-rich H/MEAs. The deformation mechanism at 298 K is mainly dislocation slip, besides FCC-to-BCC phase transformation occurs at 77 K. First-principles calculations show that Mo doping reduces the alloy's binding energy and O adsorption energy while increasing the Cl- migration barrier. Moreover, when Cl- adsorbs near Mo atoms, Mo weakens Cl- adsorption on Fe/Cr sites and reduces electronic interaction with Cl-. The experimental results show that Cr2O3 and Mo oxides in the passive film enhance the corrosion resistance of the (Fe62Co8Ni15Cr15)(97)Mo-3 MEA. This paper offers a reference for designing high-performance Fe-based MEAs.

Eutectic high and medium entropy alloys (EH/MEAs) are promising candidates for next-generation marine propellers due to their high impact toughness and corrosion resistance. This study investigates the tensile properties, impact toughness (at 298 K and 77 K), fracture behavior, and seawater corrosion resistance of as-cast AlCrFe1.5Ni2.6 EMEA. Microstructural and fractographic analyses reveal the origin of its temperature-dependent impact performance—providing critical data for marine applications. The results indicate that the alloy maintains high strength and ductility while exhibiting excellent impact toughness (42.85 J/cm2) at 298 K. At 77 K, the alloy shows a substantial increase in strength with a slight improvement in ductility, but suffers a sharp decline in impact toughness (13.9 J/cm2). The transition in the microscopic fracture mechanism from ductile-dominant to cleavage explains the decreased impact toughness. Furthermore, this work shows that the alloy also has excellent corrosion resistance in artificial seawater solution. This research supports the practical application of EMEAs.

Fe-based medium-entropy alloys (MEAs) are a cost-effective class of multi-principal-element alloys with tunable mechanical behavior. Their key advantage lies in the ability of Fe-rich, non-equiatomic compositions to regulate phase stability, deformation behavior, and strain hardening without relying heavily on expensive Co, Ni, or V. Increasing evidence shows that metastable face-centered cubic (FCC) matrices can provide excellent combinations of strength and ductility when their transformation behavior is properly controlled. Through compositional tuning and microstructural regulation, the phase stability, stacking-fault energy, precipitation behavior, and deformation pathways of Fe-based MEAs can be adjusted to achieve a balance between strength, ductility, and service reliability. This review critically synthesizes the metastability, microstructure, strengthening mechanisms, and service-oriented design principles of Fe-based MEAs. The literature discussed in this review was selected from peer-reviewed studies that report clear links among alloy composition, processing history, microstructure, deformation behavior, and mechanical or service-related properties. Unlike reviews that mainly classify alloy systems or deformation modes, this work emphasizes how metastability engineering and microstructural design can be integrated to guide application-specific alloy development. Representative Fe-rich non-equiatomic alloy systems are compared to clarify how alloying and processing regulate metastability, precipitation behavior, transformation kinetics, and strain partitioning. This review highlights that superior properties arise from the coordinated control of metastability, heterogeneous microstructures, and strengthening mechanisms. A central conclusion is that controlled transformation kinetics, rather than the pursuit of a maximum martensite fraction, is the key design variable for sustaining strain hardening and achieving stable strength-ductility synergy. Remaining challenges include quantitative deconvolution of coupled mechanisms, reliable prediction of local metastability, long-term microstructural stability, manufacturability, cost-performance balance, and integration of high-throughput experiments with computational alloy design. Overall, this review provides a service-oriented design framework for high-performance, low-cost Fe-based MEAs through the integrated control of composition, metastability, microstructure, processing, strengthening mechanisms, and application-specific performance.