Ultrafine Microstructure Research Articles

Hydrogen generation by hydrolysis of ultrafine microstructure Mg[sbnd]10Ni alloy wire

This work presents a MgNi alloy wire prepared by a combination of extrusion and multi-pass hot drawing for fast hydrogen generation from aqueous NaCl solution. The results showed that the hydrogen generation rates of the wire were significantly improved compared to the as-cast alloy. The hydrolysis of the MgNi alloy wire produced 820 ml g−1 hydrogen in 16 min and the maximum hydrogen generation rates reached 67.86 ml g−1 min−1 in 3.5 % NaCl solution and at 25 °C. The improved hydrogen production properties can be attributed to the increase in specific surface area and the ultrafine microstructure with highly dispersed submicron Mg2Ni particles of the MgNi alloy wire.

Enhanced Mechanical Properties of Cast Cu-10 wt%Fe Alloy via Single-Pass Friction Stir Processing

In this study, Cu-10 wt% Fe alloy in as-cast state was modified using friction stir processing (FSP). The microstructure evolution of Cu-10 wt% Fe alloys in different states was characterized in detail using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The results show that due to dynamic recrystallization, the FSPed Cu-10 wt% Fe alloy obtained a uniformly equiaxed ultrafine microstructure with low density of dislocation, high proportion of high-angle grain boundaries (HAGBs), and high degree of recrystallization. Fine equiaxed grains with an average size of 0.6 μm were produced after FSP. Many fine-precipitate Fe-phases with an average size of 20 nm were uniformly distributed in the Cu matrix. The FSPed samples possessed excellent mechanical properties, such as high Vickers hardness (163.5 HV), ultimate tensile strength (538.5 MPa), and good elongation (16%). This single-pass FSP method does not require subsequent aging treatment and provides a simple and efficient way to improve the properties of Cu-Fe alloys.

Evolution of ultrafine bainite microstructure during rapid heating process and the role of retained austenite

Rapid heat treatment is an important method to improve the properties of steel. Moreover, the study of the phase transformation process plays an important role in the formulation of rapid heat treatment. This paper investigates phase transformation behavior and microstructure evolution of ultrafine bainite at varying heating rates, and reveals the influence mechanism of retained austenite on austenitizing. Results showed that the decomposition of retained austenite was influenced by the diffusion of Si element. Therefore, the decomposition temperature of retained austenite is severely affected by the heating rate. Retained austenite completely transformed into cementite and ferrite when heating rate was below 5 °C/s. A small amount of retained austenite was kept when the heating rate was higher than 5 °C/s. The kept austenite effectively suppressed the hysteresis of Ac1 and resulted in a unique mechanism of austenite grain formation. When the heating rate range was 5–10 °C/s, some new austenite skipped the nucleation process and grew directly on the kept austenite, forming the large austenite grains. And other new austenite was obtained via nucleation and growth process. Thus, the grain size of bimodal distribution is formed. This leads to the phenomenon of austenite memory effect. When the heating rate was increased to 50 °C/s and higher, the austenite grain size was less than 14 μm. Therefore, rapid heating makes the phase transition lag. When the heating rate is high enough, part of the austenite is kept, which has an important influence on austenitizing process of the steel.

Improvement of strength and performance properties of copper wire during severe plastic deformation and drawing process

The paper studies the evolution of microstructure and mechanical properties of copper wire during a new combined straining process. The main point of the technological process is to strain the wire in a rotating equal-channel step die and subsequent drawing. The die rotates around the wire axis and thereby creates tension due to equal-channel angular pulling and twisting in the die. Transmission electron microscopy and EBSD analysis, as well as tensile testing and microhardness determination investigated the strained copper wire. Ultra-fine grain gradient microstructure with a high component of high-angle grain boundaries was obtained as a result of straining. The tensile strength of the strained copper wire compared to the unstrained one increases more than twice from 302 to 635 MPa, and the yield strength increases from 196 to 406 MPa. The use of such hardened copper wire in construction will reduce the weight of the structure due to the reduction of diameter.

Development of anisotropic Nd-Fe-B powder from isotropic gas atomized powder

This work presents an innovative approach to obtain anisotropic Nd-Fe-B powder from isotropic gas atomized powder. The new process was developed using a ternary Nd-Fe-B alloy, without the requirement for additional heavy rare earth or other critical raw materials. It comprises the following steps: (a) gas atomization to produce a polycrystalline isotropic powder; (b) annealing at high temperature to induce grain growth; (c) hydrogen decrepitation to obtain a monocrystalline powder; and (d) hydrogenation-disproportionation-desorption-recombination to obtain the final ultrafine anisotropic particles. The final particle shape is polygonal, which should improve the injection molding characteristics of current powder. The final powder exhibits both high remanence (0.97 T) and coercivity (1354 kA/m) for laboratory batch sizes, which is a result of its anisotropic ultrafine microstructure. Thus, gas atomization is considered a feasible alternative to casting methods as a first step to produce powders for anisotropic bonded magnet.

Hierarchical microstructure enables high strength and good ductility in as-cast Fe27Ni35Cr18.25Al13.75Co2Ti2Mo2 high-entropy alloy

As-cast alloys often require complex thermomechanical processing to obtain a hierarchical structure to achieve a good combination of strength and ductility. Here in this work, a novel hierarchical Fe27Ni35Cr18.25Al13.75Co2Ti2Mo2 high-entropy alloy (HEA) with ultra-high tensile strength and excellent ductility was fabricated by direct casting. The as-cast alloy exhibits hierarchical structure with an ultrafine lamellar microstructure (ULM), ultrafine rhombus microstructure (URM), ultrafine vermicular microstructure (UVM), nanosized precipitates and spinodal decomposition (SP) that develops during casting and cooling. The incompatibility of face-centered cubic (FCC) and body-centered cubic (BCC) phases in the deformation process leads to heterogeneous deformation-induced (HDI) hardening, which brings the alloy a tensile yield strength (YS) of ∼1056 MPa, an ultimate tensile strength (UTS) of ∼1526 MPa and a total elongation (El) of ∼15.6%. Additionally, the numerous interfaces generated by the hierarchical structure absorb the energy during deformation, effectively retarding the dislocation motion and causing strong work-hardening.

Achieving strength-ductility synergy in a laser-powder bed fused near-α titanium alloy through well-crafted heat treatments

The design of a two-step heat treatment (solutionizing and aging) protocol for laser-powder bed fused Ti-6Al-2Sn-4Zr-2Mo (L-PBF-Ti-6242) and its effect on microstructure and mechanical properties are studied. The heat treatment is designed considering the kinetics of α’ to β transformation and nanotwin annihilation with an emphasis on preserving the unique, ultrafine, and hierarchical microstructure. The solutionizing temperature of 900 °C for 10 and 20 min is selected based on the α’ to β transformation percentage. The aging temperatures of 300 °C and 350 °C for 12–72 h are chosen considering the kinetics of nanotwin annihilation. A total of 15 conditions are evaluated from these solutionizing and aging parameters including as-built, only solutionized, solutionized-aged, and direct aging. The as-built microstructure has the highest strength and lowest ductility due to the ultrafine acicular α’ martensite and dense dislocation network. The solutionized microstructure has α/α’and β phases with different dislocation densities. This condition results in the lowest strength and highest ductility, governed by the presence of the bcc phase (β), and high mean effective slip length in the α/α’ phase. The aging process (following the solutionizing step) results in changes in dislocation substructure in the α/α’ phase which leads to an increase in strength, controlled by a reduction in mean effective slip length. The formulated two-step heat treatment leads to the best strength-ductility synergy in this study.

Laser additive manufacturing of new α+β titanium alloy with high strength and ductility

The capability to control volume fraction and morphology of α phase in α+β titanium alloys makes this group of alloys a suitable choice to develop new compositions to deal with the formidable requirement of industrial development. However, further alloying is challenged because of the difficulty of uniform mixing during the melting process and the severe segregation during solidification. Due to the intense convection within small melt pool, additive manufacturing (AM) can achieve uniform concentration distribution and thus is a perfect alloying strategy to exert the potential of more species of alloying elements. To fulfil the potential of alloying, an α+β titanium alloy with new composition was additively manufactured in this study by laser directed energy deposition (LDED). The as-deposited new α+β titanium alloy exhibited near equiaxed prior β grains and intragranular ultrafine basket-weave microstructure in which the thickness of α lath is 0.4 ± 0.1 μm. A fibrous root morphology of primary α (αp) whose thickness is 1.4 ± 0.2 μm formed by macroscopic diffusion in the subsequent annealing process and this special morphology is the main reason of the improvement of ductility. With the aid of this special morphology and the nucleation of fine secondary α (αs), the ultimate tensile strength (UTS) and ductility can reach 1247±3 MPa and 9.2 ± 0.2%. The achievement of high strength and good ductility indicates that the development of new titanium alloys is suitable for AM and thus could be the future direction for titanium alloys research.

A Novel 1000 MPa Grade Ultrafine-Grained Dual-Phase Press Hardening Steel with Superior Oxidation Resistance and High Ductility.

1000 MPa grade low-carbon martensite press hardening steels (PHS) are widely used in energy-absorbing domains of automotive parts, such as the bottom of a B-pillar. To prevent oxide scale formation during hot forming, this PHS is often required to be protected by an additional Al-Si coating. In addition, although the low carbon martensitic microstructure grants it excellent bending toughness, the ductility tends to be limited. In this study, a novel 1000 MPa grade ultrafine-grained (UFG) martensite-ferrite (F-M) dual-phase (DP) PHS with superior oxidation resistance was designed using tailored additions of Cr, Mn, and Si, and refining the initial microstructure. Only 0.55 ± 0.18 μm thick oxide film is formed in the designed steel during austenitizing heating and stamping, which is significantly lower than the 24.6 ± 3.1 μm thick oxide film formed in conventional 1000 MPa grade low-carbon martensite PHS under the identical condition. The superior oxidation resistance of designed steel can be attributed to the rapid formation of the protective Si-rich, Cr-rich, and Mn-rich oxide layers during annealing. Moreover, due to the presence of ferrite and ultrafine microstructure, the designed steel also shows a significant improvement in ductility from 8.5% to 16.8% without sacrificing strength and bending toughness compared with conventional 1000 MPa grade low-carbon martensite PHS.

Ultra-fine microstructure and exceptional low coercivity developed in a high-Bs Fe-Si-B-P alloy by co-alloying Ni, Mo, and Cu

Designing soft magnetic alloys with high saturation magnetic induction (Bs) is of great importance for improving the power density of electric and electronic devices. For high-Bs nanocrystalline alloys, the main problem is the grain coarsening effect induced by high Fe content (>80 at.%), which deteriorates the soft magnetic properties. In present work, we designed new Fe-based nanocrystalline alloys by microalloying a Fe-Si-B-P alloy. The co-alloying of Ni, Mo, and Cu effectively refines the microstructure of nanocrystalline alloys from 28.5 nm to 13.1 nm and increased the stability of soft magnetic properties. Even though there are 28-nm-large surface crystallites in the amorphous precursors, an exceptional low coercivity of 1–2 A/m with a high Bs of 1.81 T was developed after nanocrystallization. These excellent magnetic properties could be maintained within a wide annealing temperature window of 50 K and an annealing time window up to 600 s for high heating rate annealing.

Ultrafine lamellar microstructures for enhancing strength-ductility synergy in high-entropy alloys via severe cold rolling process

In the present study, the effect of severe cold rolling (SCR) on the microstructure and mechanical characteristics of X0.25FeCoNiMnV (X: Al, Ti) high-entropy alloys (HEAs) specimens was investigated. It was observed that the as-cast and homogenized specimens exhibited a two-phase microstructure consisting of face-centered cubic (FCC) and a minor body-centered cubic (BCC) structure. Electron backscattered diffraction (EBSD) analysis indicated that SCR could effectively induce a strong rolling texture with stretched grains along the rolling direction and lamellar deformation bands as the major microstructural features for all the HEAs specimens. Moreover, a large number of nano-scale grains are formed within the coarse-stretched microstructure of Al0.25FeCoNiMnV and Ti0.25FeCoNiMnV HEAs specimens due to local fragmentation, resulting in a bimodal grain structure. After 85 % cold rolling, the fraction of high angle grain boundaries and mean misorientation angle of the boundaries are 54 % and 22.15° in the FeCoNiMnV specimen, while they are 61 % and 26.42° for Al0.25FeCoNiMnV, and 57 % and 28.53° for Ti0.25FeCoNiMnV. Ti0.25FeCoNiMnV specimen exhibited the best combination of strength-ductility (tensile strength of 1225 MPa and elongation of 26 %) compared to FeCoNiMnV (720 MPa and 15 %) and Al0.25FeCoNiMnV (970 MPa and 18 %). Observations revealed that the failure mode of HEAs specimens was a ductile type fracture with a combination of deep and shallow dimples. The findings revealed that SCR can effectively improve the strength and microhardness of HEAs, while it highly retains their elongation owing to the formation of a bimodal structure consisting of new grain boundaries and dislocation substructures.

Simultaneously increasing mechanical and corrosion properties in CoCrFeNiCu high entropy alloy via friction stir processing with an improved hemispherical convex tool

It generally shows the trade-off for the mechanical properties and corrosion resistance of high entropy alloys (HEAs). In this study, friction stir processing (FSP) with an improved hemispherical convex tool was applied to process the as-cast CoCrFeNiCu HEA, which simultaneously increased the mechanical properties and corrosion resistance of the HEA by a large degree. After FSP, the grains were significantly refined from 6 μm to ∼300 nm, with 91% of high angle grain boundaries and 18% of nanometer twins, leading to a remarkable increase in the yield strength from ∼194 MPa to ∼935 MPa. More importantly, the FSP HEA showed an excellent strength-ductility synergy with yield strength of ∼695 MPa and a uniform tensile elongation of ∼17.5% after annealing, which was mainly attributed to the comprehensive role of equiaxed ultrafine microstructure, second phase and the high fraction of annealing twins (27%). In addition, the FSP HEA showed higher corrosion resistance than the base material by electrochemical test, which was mainly attributed to the improvement of the self-corrosion potential and the stability of the passivation film caused by the mitigation of Cu segregation and grain refinement. This study provides a new way to simultaneously increase the mechanical properties and corrosion resistance in HEAs.

Cost-effective and facile route to ultrafine-microstructure high-entropy alloy for cryogenic applications

Industry applications of the current cryogenic high entropy alloys (HEAs) are limited by their prohibitive costs, relatively low yield strength and unknown corrosion resistance. Here, we present a cost-effective and facile approach to produce cryogenic HEAs with lower cost, exceptional mechanical properties and corrosion resistance. The key is to design a cost-effective Fe35Ni35Cr20Mo5Al5 HEA and introduce ultrafine microstructure (UFM), including ultrafine grains (∼693 nm), high density of annealing twins and nanoprecipitates, into the alloy by manipulating the concurrent precipitation and recrystallization at 940 °C within 2 min. The cost-effective UFM-HEA exhibits a temperature-dependent strain-hardening capacity and a superior strength-ductility synergy at 77 K with a yield strength of ∼1165 MPa, a tensile strength of ∼1412 MPa and a uniform elongation over 20%. The superior tensile properties at cryogenic temperature are attributed to the twining-dominated multiple deformation mechanisms and the integrated strengthening effects, including grain refinement strengthening, twin strengthening and second-phase strengthening. At the fracture strain of ∼20%, extensive microcracks formed within the nanoprecipitates without propagating into the face-cantered-cubic matrix, suggesting a high crack tolerance of the UFM-HEA at both room and cryogenic temperatures. Moreover, the UFM-HEA has a superior corrosion resistance compared to the 316L stainless steel due to the larger passivity region and higher charge transfer resistance. Such outstanding cryogenic mechanical properties and corrosion resistance together with the lower cost make the UFM-HEA superior to most cryogenic HEAs. This strategy not only sheds light on the development of new-generation cryogenic HEAs but also significantly enhances their industrial application potential.

Comparison of microstructure and mechanical properties of industrial pure aluminum produced by powder metallurgy and conventional rolling

Aluminum alloys are produced by different manufacturing techniques and each technique produces a unique microstructure. One of the most versatile manufacturing methods is powder metallurgy (P/M) because it produces a final fine or ultrafine grain microstructure. But it requires powder consolidation and densification processes after P/M. In the other side, Hot Isostatic Pressing (HIP) is now recognized as a very interesting technique to densify advanced materials with a high potential. The aims of this work are: to produce an AA1100 aluminum billet by powder densification followed by HIP and to compare its microstructure and mechanical properties against the ones of an AA1100 aluminum plate produced by conventional rolling. The mechanical properties were measured using tensile test and Charpy test. The results show that the tensile strength of the P/M+HIP sample is higher than the one of the aluminum plate, but the yield strengths are similar. In the other hand the impact toughness results are very different from each other.

Microstructure formation, corrosion properties, and tribological properties of laser-cladded CrCoNi medium-entropy alloy coatings

In this study, near-fully dense CrCoNi medium-entropy alloy coatings were deposited on an AISI 1045 steel substrate via laser cladding. Afterwards, we investigated the microstructure formation, corrosion properties, and tribological properties. Microstructural observations revealed that the CrCoNi coating has a single-phase face-centered-cubic structure and exhibits columnar grains. Furthermore, cellular substructures and elemental segregation were achieved and discussed. Potentiodynamic polarization tests in 0.1 mol/L HCl solution revealed that as compared with the AISI 1045 steel substrate, the CrCoNi coating exhibits enhanced corrosion resistance owing to a multi-stage potentiodynamic polarization behavior. Also, the dry sliding tribological tests revealed that the CrCoNi coating exhibits enhanced tribological properties due to the ultrafine microstructures and high hardness.

Large-size complex-structure ternary eutectic ceramic fabricated using laser powder bed fusion assisted with finite element analysis

Melt-grown oxide eutectic ceramics are well known for their excellent mechanical properties and microstructural stabilities at ultra-high temperatures. Laser powder bed fusion (LPBF) provides a novel technology for manufacturing materials with large sizes and complex structures. However, crack controlling is a serious challenge in this process owing to the intrinsic brittleness of ceramic materials. In this study, LPBF method is applied to fabricate Al2O3/GdAlO3/ZrO2 ternary eutectic ceramics assisted by a finite element method (FEM) to investigate an optimized process and innovatively reveal the crack formation mechanism and propagation behavior via a single track, a single layer, and multilayers. Temperature and thermal stress distributions under different process parameters are obtained. The maximum tensile stress σy (in front of and behind the edge of the molten pool) perpendicular to the scanning direction induces a longitudinal crack, the tensile stress σx (at the side rim of the molten pool) parallel to the scanning direction induces a transverse crack, and the shearing stress on the XY plane promotes the deflection of the transverse crack on one side of the single track. In the multilayer, the maximum principal stress occurs at the margin zone of the deposition. The maximum principal stress increases at the first three layers and then decreases after the fourth layer. Based on the simulation result, the as-solidified Al2O3/GdAlO3/ZrO2 eutectic ceramics with multiple shapes, such as cylindrical, cubic with round corners, triangular prism, and quadrangular, with dimensions of 30 mm (width or diameter) × 30 mm (length or diameter) × 1 mm (height) and ultra-fine eutectic microstructures (eutectic spacing of approximately 88 nm) are fabricated by LPBF, providing a significant potential to overcome the bottleneck for fabricating large-size and complex-structure ceramics directly in a single-step process. This work provides theoretic foundation and technical support for preparation of ultra-high temperature solidified oxide eutectic ceramics with ultra-fine microstructures and complex structures directly, which has great application potential in fields as aerospace, machinery, and chemical industry.

Laser additive manufacturing of strong and ductile Al-12Si alloy under static magnetic field

Rapid cooling and solidification during laser additive manufacturing (LAM) can produce ultra-fine microstructure with higher strength. However, the non-uniform cell/grain structure can easily result in early stress concentration and fracture during deformation, which remains a major challenge for the LAM field. Using Al-12Si as the model alloy, we employed the external static magnetic field (SMF) to modulate the laser powder bed fusion process (L-PBF), demonstrating a uniform microstructure with a refined cell structure. The mechanical properties show that the SMF can produce a combination of high tensile strength of 451.4 ± 0.5 MPa and large uniform elongation of 10.4% ± 0.79%, which are superior to those of previously-reported Al-Si alloys with post-treatment or element alloying. The mechanism analysis based on multi-scale simulation reveals the determining role of SMF in rapid solidification, and this method is applicable to the microstructure control of other metallic materials during LAM.

Simultaneous densification and improvement of cold spray additively manufactured Ti-6Al-4 V properties via electro-plastic treatment

Large-scale industrial application of additively manufactured (AM) components in general, and specifically cold sprayed additive manufactured (CSAM), is limited due to the nature of this technology and the resulting product’s porosity and embrittlement. To improve the final properties of additively manufactured material, many lengthy, complex, or expensive post-treatments have been proposed. Reducing the environmental impact, cost, and time required for additive manufacturing will allow for greater use in industrial applications. A novel thermomechanical treatment known as in situ electro-plastic treatment (ISEPT) is used in this study to treat CSAM Ti-6Al-4 V alloy known as grade 5 titanium. The Ti-6Al-4 V alloy has approximately three times the strength and hardness of commercial purity titanium (CP-Ti) with lower ductility and a dual-phase (α + β) microstructure that poses challenges during the CSAM process. Compared to CP-Ti, the results showed that CSAM Ti-6Al-4 V presented double the porosity and triple the number of ISEPT passes that presented ~ 2 µm ultra-fine grain microstructure. The ultimate tensile strength (UTS) of the ISEPT material was superior to that of CSAM Ti-6Al-4 V and increased from 184 to 1096 MPa with improved ductility rise from 1.1 up to 8.8%. Six ISEPT passes in air resulted in a slight increase in oxygen from 0.2% in the as-CSAM condition to 0.35%. Tensile properties of the ISEPT material were comparable to wrought Ti-6Al-4 V with 989 MPa UTS and 8.3% elongation. The ISEPT passes consolidated the CSAM (α + β) dual-phase Ti-6Al-4 V and allowed for the nucleation of equiaxed grains at the vicinity of former CSAM splat boundaries. The formation of lamellar colonies within the splat’s inner regions was observed. The role of ISEPT conditions on the rapid elimination of porosity and the evolution of cold spray splat boundaries via dynamic recrystallization were discussed.

A Comparative Study of Metakaolin and Silica Fume on the Properties and Microstructure of Ultrafine Dredged Sand Mortars

The main objective of this study is to improve the performance of ultrafine dredged sand mortars by using metakaolin (MK) and silica fume (SF) mixed with high-content FA. The mechanical properties and microstructure of the ultrafine dredged sand mortars were analyzed. The results show that the strong growth rate of the mortars with 5%, 10%, and 15% MK and SF contents, respectively, exceeds 30% at the age of 7 d. Compared with an ordinary Portland cement dredged mortar, the shrinkage of the specimens with 5% and 15% MK increases prior to 7 d and decreases by 16.9% and 13.8%, respectively, at 90 d. The addition of MK shows a better enhancement effect than that of SF, with the splitting tensile strength increased by 41.4% to 2.15 MPa with 15% MK compared with the mortar with a 50% FA content at 3 d. MK shows a higher enhancement effect than SF due to its uniquely active Al2O3. Moreover, a microstructural investigation based on scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) confirms that the physical filling and pozzolanic effects of MK and SF can optimize the microstructure of the slurry, improve the interfacial combination of different phases, and refine the pore size distribution of cement paste. The test results prove that high-content FA ternary cementitious systems containing MK or SF represent a sustainable solution to the resource utilization of building materials based on ultrafine dredged sand.

Cryo-rolling and annealing-mediated nano/ultrafine structure, texture, and properties of extremely low stacking-fault energy high entropy alloys: Comparative perspectives

The effect of heavy (∼90% thickness reduction) cryo-rolling (CryoR) on microstructure, texture, and tensile properties of an extremely low stacking fault energy (SFE) Co20Cr26Fe20Mn20Ni14 high entropy alloy (HEA) was investigated. Comparisons with other heavily cold- (CR)/cryo-rolled materials were also presented to highlight the effect of CryoR. CryoR resulted in the formation of heterogeneities, shear bands, deformation twins, stacking faults, and deformation-induced nano-lamellar structure with a spacing of 35 ± 8 nm. Remarkably, the nano-grain size after CryoR was smaller than other low SFE alloys and achieved at a much lower strain level. These outcomes indicated the combined effect of CryoR, massive solid-solution formation, and extremely low SFE towards extreme grain refinement. CryoR also resulted in the development of a strong brass texture ({110}<112 >), similar to other low SFE alloys. Annealing resulted in recrystallization, precipitation, and dissolution of Cr-rich tetragonal σ phase precipitates in the CryoR material at lower temperatures due to finer nanostructure and greater stored energy for transformation. Grain growth was inhibited up to 950 °C by the presence of the σ precipitates but was triggered beyond that by the dissolution of the precipitates. Annealing textures retained weak α-fiber (normal direction (ND)//<110>) components and a high fraction of random components, which resembled other low SFE HEAs. Meanwhile, ultrafine microstructures and multistage strain-hardening resulted in a remarkable ambient temperature strength-ductility (1025 MPa-20%) combination in the CryoR and annealed HEA.