Ultrafine Grains Research Articles

Grain size effect on the phase growth in CoNi/Sn sandwich diffusion couples

Grain size effect during interdiffusion is investigated by designing a sandwich couple of CG-CoNi/Sn/UFG-CoNi; (CG coarse grained (>200 µm), UFG: ultrafine grained (∼240 nm)). Phase growth is examined at temperatures 175 & 200 ℃ for various times. CG CoNi and UFG CoNi have been fabricated by Vacuum arc melting and spark plasma sintering of mechanically alloyed CoNi powders, respectively. At 175 ℃, (CoNi)Sn3 intermetallic phase is detected at CG CoNi/Sn interface and (CoNi)Sn2 phase at UFG CoNi/Sn interface. At 200℃, formation of (CoNi)Sn2 and (CoNi)Sn3 phases is observed at CG interface and only (CoNi)Sn2 at the UFG interface. Phase compositions have been confirmed by electron probe microanalysis while the corresponding crystal structure with micro-x-ray diffraction. Phase selection in the interdiffusion zone (IDZ) of CG CoNi/Sn is governed primarily by kinetic factors, while thermodynamic driving forces, assessed using CALPHAD approach, also contribute to phase formation in the IDZ of UFG CoNi/Sn. Time-dependent measurements at 175 & 200℃ for UFG CoNi/Sn reveal an accelerated growth of phases when compared with the CG CoNi/Sn. The enhanced kinetics and preferential formation of the (CoNi)Sn2 phase at the UFG CoNi/Sn interface can be ascribed to the higher proportion of grain boundaries (GBs), leads to an increase in overall diffusion flux. The sandwich diffusion couple approach ensured that all the comparisons between CG and UFG interfaces are conducted under similar conditions yielding dependable correlations. The formation of intermetallic phases and role of GBs are studied at a finer detail using correlative microscopy approach.

Creep in a nanocrystalline VNbMoTaW refractory high-entropy alloy

Refractory high-entropy alloys (RHEAs) are considered to be a promising candidate for elevated temperature applications. Nanocrystalline (NC) RHEAs are supposed to exhibit many different high-temperature mechanical behaviors in comparison with their coarse-grained (CG) and ultrafine-grained (UFG) counterparts. However, the creep behaviors of NC RHEAs, which must be well evaluated for high-temperature applications, are largely unknown because it is difficult to produce bulk quantities of NC RHEAs for creep tests. In the present work, an equiatomic bulk NC VNbMoTaW RHEA with an average grain size of 67 ± 17 nm was synthesized by mechanical alloying (MA) and the subsequent high-pressure/high-temperature sintering. The creep tests were performed on bulk specimens by compression at high temperatures (973 and 1073 K) under different stresses (70–1100 MPa). The creep resistance of the bulk NC VNbMoTaW is slightly lower than that of the bulk CG VNbMoTaW, but much higher than that of previously reported CG and UFG HEAs. The derived activation volume, stress exponent, and activation energy of bulk NC VNbMoTaW indicate that the creep deformation is dominated by grain boundary diffusion. The creep deformation is controlled by the diffusion of Mo and Nb elements, which have the two slowest grain boundary diffusivities among the five alloying elements. The present work provides a fundamental understanding of the creep behavior and deformation mechanism of NC RHEAs, which should help design advanced creep-resistant RHEAs.

The Microstructural Evolution and Corrosion Behavior of Zn-Mg Alloys and Hybrids Processed Using High-Pressure Torsion.

Zinc (Zn) alloys, particularly those incorporating magnesium (Mg), have been explored as potential bioabsorbable metals. However, there is a continued need to enhance the corrosion characteristics of Zn-Mg alloys to fulfill the requirements for biodegradable implants. This work involves a corrosion behavior comparison between severe-plastic-deformation (SPD) processed cast Zn-Mg alloys and their hybrid counterparts, having equivalent nominal compositions. The SPD processing technique used was high-pressure torsion (HPT), and the corrosion behavior was studied as a function of the number of turns (1, 5, 15) for the Zn-3Mg (wt.%) alloy and hybrid and as a function of composition (Mg contents of 3, 10, 30 wt.%) for the hybrid after 15 turns. The results indicated that HPT led to multimodal grain size distributions of ultrafine Mg-rich grains containing MgZn2 and Mg2Zn11 nanoscale intermetallics in a matrix of coarser dislocation-free Zn-rich grains. A greater number of turns resulted in greater corrosion resistance because of the formation of the intermetallic phases. The HPT hybrid was more corrosion resistant than its alloy counterpart because it tended to form the intermetallics more readily than the alloy due to the inhomogeneous conditions of the materials before the HPT processing as well as the non-equilibrium conditions imposed during the HPT processing. The HPT hybrids with greater Mg contents were less corrosion resistant because the addition of Mg led to less noble behavior.

DEVELOPMENT OF RECOMMENDATIONS FOR THE IMPLEMENTATION OF COMBINED DEFORMATION TREATMENT “ECAP-DRAWING” INTO PRODUCTION

Combined innovative technology developed in this article makes it possible to produce bimetallic long products in the form of bars and wires with improved mechanical properties, due to the ultrafine grain structure of the material, with less energy and labor costs and implementation of continuity principle in industrial enterprises of metal-working industry. The combination of equal-channel angular pressing with drawing makes it possible not only to harden the composition, but at the same time to preserve important and regulated by a number of GOST plastic properties of the products. This circumstance favorably distinguishes the method under study from other (traditional) types of deformation treatment.

HFMI-induced fatigue strength improvement of S355 steel transverse non-load-carrying attachments with lack of fusion in the weld root

The effects of high-frequency mechanical impact (HFMI) treatment and preloading on the fatigue behaviour of the S355 steel transverse non-load-carrying attachments welded with technological defect (‘lack of fusion’) in the weld root are studied. The S355 steel joints were purposely welded with incomplete penetration (a technological defect of 3x3 mm formed over the entire weld root length). As established, this technological defect does not affect the fatigue life since the crack initiation and propagation occur along the weld toe. HFMI leads to a tenfold increase in fatigue life of the joints with technological defects. Preloading the as-welded joints at maximum alternating stress of 260 MPa for 64,000 cycles leads to partial relaxation of tensile residual stresses. HFMI transforms tensile stresses into compressive ones in both non-preloaded and preloaded samples. Compressive stresses of 315 MPa and 100 MPa were respectively registered at distances of 3 mm and 13 mm from the HFMI-formed groove using the hole-drilling method and electron speckle interferometry. Transmission electron microscopy of the weld-heating affected zone reveals that the bimodal microstructure, containing the areas with ultrafine and larger grains, observed after sequentially applied preload and HFMI remains stable during further fatigue cycling and facilitates the enhanced fatigue strength/life.

Низкотемпературная сверхпластическая деформация никелевого сплава ЭК79 с ультрамелкозернистой структурой смешанного типа

One of the most effective ways to increase the processing plasticity of advanced superalloys (heat-resistant nickel-based alloys) is the formation of an ultrafine-grained (UFG) microstructure in bulk semi-finished products. Such a microstructure is a necessary condition for the manifestation of the structural superplasticity effect in the technological processes of manufacturing products from such superalloys. One of the most promising methods for producing UFG microstructures is thermomechanical treatment (TMT) according to the multiple isothermal forging scheme. It has been shown that the EK79 superalloy after TMT, with a gradual decrease in the processing temperature from 0.88 to 0.62 Ts (where Ts is the strengthening phase dissolution temperature) leads to the transformation of the initial microduplex fine-grained microstructure into a mixed UFG microstructure. Such a mixed UFG microstructure consists of: 1) relatively coarse (inherited from the fine-grain microstructure) particles – γ'-phase with a size of 3.0±0.8 μm; 2) γ-grains, and incoherent γ'-phase particles with a size of 0.3–0.5 μm; 3) strengthening coherent intragranular γ'-phase particles with a size of 0.05–0.1 μm, released upon cooling from the TMT temperature to room temperature. During uniaxial compression tests, the EK79 superalloy with such microstructure, demonstrates low-temperature superplasticity in the temperature range of 800–1000 °C. It has been found that an increase in the deformation temperature up to 1000 °C, leads to the increase of γ-phase grains to micron size. The maintenance of superplastic properties in the presence of relatively coarse incoherent particles in the microstructure of the second phase (γ'-phase) is apparently related to the fact that the deformation is localised in the UFG component.

Interfacial reactions in Ta/304L and Ta/Cu/304L composites during single-shot explosive welding and post-processing annealing

This work presents a study of recent advances in the understanding of the mechanism controlling chemical composition and the microstructure of reaction regions in a Ta/304L steel composite with and without Cu interlayers fabricated by explosive welding, both during composite formation and post-processing annealing. The microstructure of solidified melt regions (SMR) were characterized using scanning and transmission electron microscopy while phase composition by X-ray synchrotron radiation. It was found that SMR in Ta/304L plates are composed of ultra-fine-grained microstructure with a varied chemical compositions, containing elements from both combined sheets. In Ta/Cu/304L composites the melted regions located close to Ta/Cu interface composed only of a combination of Cu and Ta (small dendrites and ultra-fine grains), when the areas near the Cu/304L interface consisted of nano-grains with a more diverse chemical composition, containing elements from both sheets. No significant effect of the annealing (under the applied temperature of 700°C and for times up to 103 h) on changes in the microstructure of the SMR was observed in both plates.

Microstructure and thermal properties of dissimilar M300-CuCr1Zr alloys by multi-material laser-based powder bed fusion

AbstractMulti-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-conductive CuCr1Zr with hard M300 tool steel. Two interface configurations of M300 on CuCr1Zr and CuCr1Zr on M300 were investigated. Ultra-fine grains form at the interface due to the low mutual solubility of Cu and steel. The material mixing zone size is dependent on the configurations and tunable in the range of 0.1–0.3 mm by introducing a separate set of parameters for the interface layers. Microcracks and pores mainly occur in the transition zone. Regardless of these defects, the thermal diffusivity of bimetallic parts with 50vol% of CuCr1Zr significantly increases by 70%–150% compared to pure M300. The thermal diffusivity of CuCr1Zr and the hardness of M300 steel can be enhanced simultaneously by applying the aging heat treatment.

Comparison of Mechanical Properties in Ultrafine Grained Commercial-Purity Aluminum (A1050) Processed by Accumulative Roll Bonding (ARB) and High-Pressure Sliding (HPS)

Comparison of Mechanical Properties in Ultrafine Grained Commercial-Purity Aluminum (A1050) Processed by Accumulative Roll Bonding (ARB) and High-Pressure Sliding (HPS)

Effects of Die Entry Angle on the Mechanical Properties of Extruded Lead Alloy

The use of lead to produce wire, power cable sheathing, guide plates, and other wide-range applications require fine-grain structures. Researchers adopted severe plastic deformation, as a means of attaining ultra-fine grain structure. However, this technique is rather expensive and time-consuming. Thus, this study is focused on the application of a simple extrusion technique to achieve fine grain structure in the lead alloy by using different die entry angles to study the microstructural and mechanical properties of lead alloy. Lead alloy samples were cast into cylindrical billets in a sand mould, machined, and tapered at the edge to ease entry into the die for the extrusion process. The die tools were made of mild steel with die entry angles of 15°, 30°, 45°, 60°, 75°, and 90°. Subsequently, the extrusion was performed with the aid of a hydraulic press machine that provided pressure on a cylindrical punch and forced the billet through the extrusion die. The mechanical and microstructural properties were studied, using the micro-hardness tester and metallurgical microscope, respectively. The results show that the maximum extrusion stress of 70 MPa of lead alloy occurred at a die entry angle of 45°, which is three times that of the conventional alloy (18 MPa) with crystal clustering and fine microstructure. The ductility of lead alloy improved when processed at a 60° die entry angle with extrusion stress of 63.3 MPa, with no significant increase in hardness with die entry angles (7.7-9.0 HV). The grains show an appreciable reduction in size and enhanced surface finish

Combined severe plastic deformation processing of commercial purity titanium enables superior fatigue resistance for next generation implants

Commercial purity titanium (cp-Ti) is considered for replacing Ti64 as an implant material in various applications, due to the potential toxicity associated with the release of Al and V ions. However, the mechanical properties of cp-Ti, particularly fatigue resistance, are inadequate for this purpose. In this study, cp-Ti grade 4 rods were processed using a combination of equal channel angular pressing and rotary swaging (ECAP/RS). Tensile and fatigue tests were conducted, along with detailed microscopy and evaluation of corrosion resistance and biocompatibility. An average yield strength of 1383 MPa was obtained while maintaining moderate ductility of 10 %. This represents the highest strength ever recorded for cp-Ti, even exceeding that of Ti64. Additionally, fatigue endurance limit increased by 43 % up to 600 MPa, almost obtaining that of Ti64. Strengthening mechanisms were attributed to the ultrafine-grained (UFG) microstructure generated by ECAP/RS, along with strong crystallographic texture and formation of sub-grain structure. Furthermore, the corrosion resistance and biocompatibility of cp-Ti were largely unaffected, potentially easing regulatory transition in future medical devices. Thus, these results demonstrate high potential of combined ECAP/RS processing to manufacture UFG cp-Ti grade 4 materials that prospectively allow for the substitution of questionable alloys and downsizing of medical implants.

Facile construction of type-II Sn-doping BiOCl/WO3 heterojunction with enhanced visible-light response and charge separation toward the application in photocatalysis

In order to effectively address the global environmental issue and energy crisis, developing a satisfying photocatalyst with high solar response and efficient carrier separation efficiency is promising and still challenging. In this study, a feasible and effective strategy from the perspective of multi-scale regulation that integrating element doping and heterostructure construction as well as morphology control is used to improve the degradation efficiency in antibiotic removal. A Sn4+ doped BiOCl (BOC–Sn) integrated Sn-doped WO3 (WO3–Sn) photocatalyst with propelling photocatalytic degradation for tetracycline (TC) was fabricated via one-pot thiourea-assisted hydrothermal method and as-obtained catalysts were denoted as (BOC–WO)–Sn-Tux (x is the molar amount of thiourea in the synthesis). By regulating the content of thiourea, the optimized (BOC–WO)–Sn-Tu1 photocatalyst exhibits ultrafine grain size, expanded visible-light response and fast carrier transport. Driven by visible light, the TC dissociation rate mediated by (BOC–WO)–Sn-Tu1 surpassed that of BOC-WOwith a photodegradation rate constant k-value 5.75 times higher than that of WO3–Sn. Analysis of energy band configuration in the BOC-Sn and WO3–Sn photocatalyst suggests that these modifications can effectively promote the photocarriertransport with type-II at the heterojunction interfaces and passivate trap sites that reside within the (BOC–WO)–Sn-Tu1 catalysts. Benefited from the stronger reduction potential, •O2− with high yield acts as the crucial active species in the photocatalytic reaction system verified by the trapping experiments and electron paramagnetic resonance (EPR) spectra detection. This work opens a new route in designing an effective photocatalytic system by integrating element doping and heterostructure construction as well as morphology regulation for environmental remediation.

Design, Finite Element Analysis and Optimization of Helical Angular Pressing (HAP) Method as a Novel SPD Technique

Severe Plastic Deformation (SPD) processes improve the mechanical properties of materials by obtaining Ultra Fine Grained (UFG) materials, orienting the grains and reforming the grains. Helical Angular Pressing (HAP) is a newly proposed Severe Plastic Deformation (SPD) method. In order to improve the efficiency of the HAP method, its die geometry should be optimized first. In this context, four parameters (helical diameter, helical pitch, helical height and channel radius) were determined for the die channel geometry, each with four levels according to the literature. Then, thanks to Taguchi L16 combinations, 16 Finite Element Analyses (FEA) were carried out using Deform 3D software instead of 256 simulations, and effective strain values and maximum pressing load values were obtained. Later on, using the SPSS 16 software, Taguchi optimization was carried out to obtain the optimum HAP die channel geometries by minimizing the press load and maximizing the effective strain values. Next, the Finite Element Analysis (FEA) was repeated with these determined optimum die channel parameters. Finally, the efficiency of this novel HAP method was compared with conventional Equal Channel Angular Pressing (ECAP) and Twist Extrusion (TE) methods. As a result, HAP method provides effective strain values equivalent to 10 number of passes after processing with ECAP. And it is approximately 4 times higher than that achieved by TE processing. As a result of the Taguchi optimization, it is concluded that the values in the combination of diameter (d)=60 mm, height (h)=50 mm, radius (r)=4 and pitch (p)=1.25 are the optimum die geometry. In conclusion, these results indicate that the proposed novel HAP method is an efficient and applicable SPD technique.

Regulating microstructure and improving precipitation hardening response of fine-grained Mg-RE-Ag hot-extruded alloy by extreme short-time heat treatment

The difficulty in exerting beneficial effects of fine grains, high number density nano-precipitates as well as weakened texture simultaneously is currently the bottleneck limiting the development of high performance (high strength, high plasticity, and isotropic) age-hardenable Mg-RE alloys. The key difficulty is that the generation of excessive dynamic precipitates is always accompanied by the formation of fully dynamic recrystallized ultrafine grains during thermal deformation, causing a significant depletion of solutes within the entire matrix and finally seriously weakening the subsequent aging nano-precipitation. In this work, the process of extreme short-time (2 min) heat treatment (ESHT) followed by peak aging treatment is applied to an ultrafine-grained weak-textured Mg-RE-Ag as-extruded alloy with numerous dynamic precipitates. The precipitation hardening response is dramatically increased (ΔHV = 37.2 HV) and the yield strength is increased by nearly 50 MPa. This is attributed to the fact that concentration of main solutes in matrix is greatly increased within only 2 min of heat treatment promoting the precipitation of nano-precipitates (prismatic β′ and basal γ′′) in the absence of excessive grain growth. The large difference between the initial and equilibrium solute concentrations, the extremely short distance required for solute diffusion within sub-microscale grains, and the effective pinning of grain boundaries by excess dynamic precipitates are responsible for the unusual microevolution during the ESHT. In addition, the formation of precipitation-free zones (PFZs) is attributed to ‘uphill’ diffusion during aging, and novel γ′′-PFZs and β′-PRZs are found. The ESHT followed by peak aging treatment provides a new way to simultaneously exert the beneficial effects of fine grains and high number density nano-precipitates.

Enhancing the electrochemical performance of Sn-Zn alloy anode foil for lithium-ion batteries through microstructure design via accumulative roll bonding technique

In this study, we introduce a novel method for designing microstructures of Sn-45Zn alloy foils utilizing the accumulative roll bonding (ARB) technique, which is one of severe plastic deformation techniques that have been used for refining the microstructures of bulk metals. The electrochemical properties of Sn-Zn foil anodes with various microstructures achieved through the ARB method followed by annealing are investigated in lithium-ion batteries. The degree and characteristics of microstructural damage during electrochemical cyclic tests are also examined in detail to provide insights into the microstructural parameters that critically influence the capacity and cyclic behavior of the Sn-Zn alloy foil anode. Our findings suggest that the ARB-processed Sn-Zn alloy foil, characterized by nearly ultrafine grains composed of Sn and Zn phases with the Zn phase forming a continuous network, exhibits superior battery capacity and cycle life compared to the sample processed using the conventional rolling method. This superiority can be attributed to its unique microstructure obtained through ARB, which reduces pore density, suppresses pore interlinkage, decreases charge transport resistance and nucleation overpotential, and enhances Li-ion diffusivity in the electrode.

Tailoring nanoprecipitates to achieve ultrahigh strength (CoCrNi)94.5W3Ta2.5 medium-entropy alloys

Metallic materials with high mechanical performance are in constant demand by various engineering applications. However, most conventional strengthening mechanisms inevitably suffer from fiercely sacrificing ductility, which severely limits service safety of metallic alloys, especially under various harsh circumstances. In this work, a novel ultra-strong (CoCrNi)94.5W3Ta2.5 medium entropy alloy (MEA) with dual nanoprecipitates is successfully developed. By conducting multiple thermomechanical processes, not only quantities of coherent γ" nanoprecipitates with D022 superlattice are introduced, but also massive semi-coherent η nanoprecipitates with hexagonal D024 superlattice are reconstructed with appropriate sizes and distributions, meanwhile ultrafine grains are achieved, together enabling superior strength-ductility synergies. This MEA exhibits not only high tensile strength of about 1.7 GPa and ultimate elongation of 23.8 % at room temperature, but also ultra-high tensile strength of about 2.2 GPa and still sufficient ultimate elongation of 13.2 % at cryogenic temperature. In-depth microstructure characterization indicates that the nanoprecipitates are effective barriers to dislocation motion at the early stages of plastic deformation. Intriguingly, the slip and deformation twinning could be transmitted across the phase boundaries with increasing applied strain, ensuring both strength enhancement and plasticity maintenance. At cryogenic temperature, much more complex deformation mechanisms are activated, e.g., multiple slip systems and high-density deformation twins, facilitating even better mechanical properties. The design concept of strengthening materials via tailoring dual coherent nanoprecipitates may afford a paradigm to develop advanced metallic materials with ultrahigh strength.

Wear mechanism transforming of ultrafine-grained pure titanium by multi-axial forging and low-temperature annealing

The effect of microstructure and mechanical properties of submicro grained commercial pure titanium (CP–Ti) on the wear mechanism is still unclear. In the present work, CP-Ti samples were subjected to multi-axial forging (MAF) and low-temperature annealing treatment to prepare ultrafine-grained (UFG) material. The mechanical properties, microstructure, and tribological characterization between coarse-grained (CG) sample and UFG samples were comparatively studied. The results showed that the MAF sample could reach a grain size of 165 nm, while its grains coarsened slightly after low-temperature annealing. The MAF sample had the highest strength and hardness and the lowest coefficient of friction, but only a 7.3 % decrease in wear rate compared to the CG sample. The 400 °C annealed MAF sample possessed a good combination of tensile strength (814 MPa) and elongation (18.6 %), resulting in the lowest wear rate of 16.8 × 10−5mm3/(N∙m). The dominated wear mechanisms of the CG sample, MAF sample and 500 °C annealed MAF sample were abrasive wear, adhesive wear and delamination wear, while the primary mechanism of the 400 °C annealed MAF sample was abrasive wear and adhesive wear. It was found that the wear mechanism transforming, higher hardness and sufficient work hardening could be responsible for lower wear rate of the 400 °C annealed MAF sample. The 400 °C annealed MAF sample showed a thinner and more homogeneous deformation layer near the worn surface, and its thickness of deformation layer was about 8 μm.

Microstructure and mechanical properties of AlTiCrFe and AlTiCrCu alloys processed by Laser Powder Bed Fusion

Additive manufacturing (AM) of aluminium alloys urges new alloy compositions to meet the requirements for high-strength and processability of the engineering products. This research focuses on the development of two Al alloys, AlTiCrFe and AlTiCrCu, with the goal to exploit the potential of transition element additions for grain refinement and increasing strength. Robust processability and build rates are reached for the two alloys, with no cracks and high density up to 99.8%. AlTiCrFe shows a bimodal microstructure, with the presence of ultrafine and fine grained zones, that can be attributed to a dual precipitation stage. Al3Ti precipitates are present in the ultrafine grained zone, confirming the effectivity of Ti as grain refiner. In addition, Al6Fe precipitates are present in the fine grained region, as a consequence of the later precipitation stage. AlTiCrCu, on the contrary, shows an homogeneous ultrafine grain microstructure, with Cu segregating at the grain boundaries. SAED analyses confirm the phase identification with the presence of high volume density cubic precipitates of Al3Ti_L12. AlTiCrFe and AlTiCrCu exhibit a yield strength value of 363 ± 1 MPa and 340 ± 1 MPa, respectively. These findings indicate that the two alloys open up new possibilities for a novel class of aluminium alloys for AM, leveraging the incorporation of transition elements, which aids in achieving strength during the as-built state, eliminating the requirement for supplementary heat treatment.

Effect of laser shock peening on the dissolution of precipitates and pitting corrosion of AA6061-T6 with different original surface roughness

The effect of laser shock peening (LSP) on the electrochemical corrosion behavior of AA6061-T6 with different original surface roughness in the 3.5 wt% NaCl solution was investigated by surface morphology measurement, microstructural characterization, and electrochemical corrosion testing. The results show that LSP improves passivation current density by 76.6%− 78.2% and polarization resistance by 287.2%− 288.9%, but does not change the influence law of the surface roughness on the corrosion behavior of aluminum alloy. LSP promoted the complete dissolution of nano-sized Al8Fe2Si particles, generation of ultrafine grains, and local dissolution of micron-sized Al8Fe2Si particles, contributing to the improved corrosion resistance.

Heterostructural nanolamellar oxide-dispersion-strengthened ferritic alloy with exceptional strength and ductility

Nanostructured ferritic alloys (NFAs) have demonstrated exceptional mechanical properties (strength and creep resistance) and radiation tolerance. However, the high strength (typically above 1.5 GPa) always comes with a significantly limited ductility. Here, we report a novel heterostructural nanolamellar ferritic alloy (NLFA) with microcrystalline (MC) domains (∼ 35 % of volume fraction) dispersed in an ultrafine-grained (UFG) matrix (∼ 500 nm grain size), enabling the alloy to achieve ultrahigh yield strength of 2 GPa and an excellent tensile elongation of ∼ 13 %. The nanolamellar-shaped grains remarkably strengthen the alloy via grain-boundary strengthening. The soft MC domains can effectively suppress the microcrack initiation and propagation along the oxide-rich preliminary powder boundaries (PPBs) via local plastic deformation. Moreover, linear oxide bands can induce numerous interlayer cracking and trigger delamination toughening, collaboratively ensuring the alloy a large ductility. The present study opens a new frontier toward high tensile ductility for the most cutting-edge ultra-strong NFAs.