Ultrahigh Ultimate Tensile Strength Research Articles

Regulation of cryogenic mechanical behaviors of C-added non-equiatomic CoCrFeNiMo ferrous medium-entropy alloy via control of initial microstructure

This study demonstrated the potential for customizing the desired properties of the Co18.5Cr12Fe55Ni9Mo3.5C2 (at.%) ferrous medium-entropy alloy by manipulating the deformation-induced martensite transformation (DIMT) behavior at liquid nitrogen temperature. This was achieved by modifying various initial microstructures through annealing at temperatures ranging from 900 to 1200 °C. The variations in DIMT kinetics were analyzed based on two main factors. (1) Inducing carbide precipitation by annealing at 900 and 1000 °C results in changes in the composition within the matrix, which may affect the stability of the face-centered cubic phase. Samples with a higher volume fraction of the carbide precipitates exhibit lower ΔGFCC→BCC and faster DIMT kinetics. (2) The onset and kinetics of DIMT are also affected by the use of martensite nucleation sites, which may vary depending on the presence of non-recrystallized regions or the grain size. In fine-grained structures, martensite primarily nucleated in the non-recrystallized regions and grain boundaries. However, in coarse-grained microstructures, martensite mainly nucleated along the in-grain shear bands and their intersections. This precise control of the microstructure results in superior properties. The samples annealed at 900 and 1000 °C with carbide precipitates and fine grains exhibit ultrahigh ultimate tensile strength, which may reach elevated values up to ∼1.8 GPa, while those annealed at 1100 and 1200 °C with larger grains and no precipitates exhibit a uniform elongation that exceeds 100 %.

Revealing precipitation behavior and mechanical response of wire-arc directed energy deposited Mg-Gd-Y-Zr alloy by tailoring aging procedures

Mg-Gd-Y-Zr alloy, as a typical magnesium rare-earth (Mg-RE) alloy, is gaining popularity in the advanced equipment manufacturing fields owing to its noticeable age-hardening properties and high specific strength. However, it is extremely challenging to prepare wrought components with large dimensions and complex shapes because of the poor room-temperature processability of Mg-Gd-Y-Zr alloy. Herein, we report a wire-arc directed energy deposited (DED) Mg-10.45Gd-2.27Y-0.52Zr (wt.%, GW102K) alloy with high RE content presenting a prominent combination of strength and ductility, realized by tailored nanoprecipitates through an optimized heat treatment procedure. Specifically, the solution-treated sample exhibits excellent ductility with an elongation (EL) of (14.6 ± 0.1)%, while the aging-treated sample at 200 °C for 58 h achieves an ultra-high ultimate tensile strength (UTS) of (371 ± 1.5) MPa. Besides, the aging-treated sample at 250 °C for 16 h attains a good strength-ductility synergy with a UTS of (316 ± 2.1) MPa and a EL of (8.5 ± 0.1)%. Particularly, the evolution mechanisms of precipitation response induced by various aging parameters and deformation behavior caused by nanoprecipitates type were also systematically revealed. The excellent ductility resulted from coordinating localized strains facilitated by active slip activity. And the ultra-high strength should be ascribed to the dense nano-β′ hampering dislocation motion. Additionally, the shearable nano-β 1 contributed to the good strength-ductility synergy. This work thus offers insightful understanding into the nanoprecipitates manipulation and performance tailoring for the wire-arc DED preparation of large-sized Mg-Gd-Y-Zr components with complex geometries.

Crafting high-strength and ductile powder metallurgy Ti6Al4V alloy with a multi-scale microstructure

In this work, a novel multi-scale microstructure of Ti6Al4V duplex alloy with nano-sized β particles was designed based on powder metallurgy. The common lamellar structure was carefully adjusted to reveal the complex effects of microstructure on mechanical properties. The ideal microstructure transforms into a composition dominated by sparse equiaxed primary α, lots of β-nanoprecipitates, and traces of secondary acicular α′ by heat treatment. The uniform nucleation of nano-sized β particles, driven by intragranular element concentration difference and local distortions, is a pivotal reason for high yield strength by dispersion strengthening. More phase boundaries also act as sustainable sources for geometrically necessary dislocations. An uncoordinated phase interface relationship from variant selection improves strain-hardening ability. The intragranular misorientation causes the value inhomogeneity of the Schmid factor in primary α, resulting in an auxiliary slip effect that benefits ductility. Therefore, the fabricated Ti6Al4V alloy displays an ultrahigh ultimate tensile strength of 1329 MPa, yield strength of 1223 MPa, and reasonably large elongation of 8.5 %, respectively. This work underscores the intricate interplay of microstructure evolution and deformation mechanisms in powder metallurgy duplex titanium alloys, offering valuable insights into enhancing the mechanical properties.

Strong room temperature work hardening in a dual heterogeneous structured ferrous medium entropy alloy

In this work, a novel (Fe65Ni15Cr10Co10)92Ti5Al3 medium-entropy alloy (MEA) with a dual heterogeneous structure was produced by adding Ti and Al in our previous reported Fe65Ni15Co10Cr10 MEA. The dual heterogeneous structure consists of the partial recrystallization matrix and heterogeneous nanoprecipitates. The tensile tests show that the MEA displays an ultra-high ultimate tensile strength (1519 MPa) and work hardening extent (559 MPa) at room temperature. The addition of Ti and Al produces precipitates while lowering FCC stability. This contributes to a continuous FCC→BCC martensitic transformation and a consequent transformation-induced plasticity (TRIP) effect during whole plastic deformation. Therefore, the excellent mechanical properties are attributed to the synergism of multiple mechanisms, including the hetero-deformation induced (HDI) strengthening, precipitation strengthening, and TRIP effects. The alloy design strategy in this paper has guiding significance for the development of high-performance ferrous MEAs.

Significantly enhanced strength-ductility synergy in an ECAP processed Zn-3.5Ag-0.08Mg alloy via lowering processing temperature

In this work, Zn-3.5Ag-0.08Mg alloys processed by equal channel angular pressing (ECAP) at three different temperatures (250 °C, 150 °C, and room temperature (RT)) were investigated, with a focus on the effects of processing temperature on the microstructure and mechanical properties. Interestingly, the strength and ductility of ECAP processed alloys improve simultaneously as the processing temperature drops from 250 °C to RT. The alloy processed at RT exhibits mechanical performance much superior to that of other Zn–Ag based alloys reported by previous studies. Specifically, the alloy has an ultrahigh ultimate tensile strength (UTS) of 465.8 MPa and an excellent elongation (EL) of 44.2%, larger than that required by medical implants by 55.3% and 121.0%, respectively. It is worth mentioning that the UTS of 465.8 MPa is the largest one ever reported in Zn–Ag based alloys. Mechanisms of the excellent mechanical performance and the variation of strength and ductility with processing temperature were unveiled. This study provides useful guidance for developing high-performance Zn alloys.

Development of Fe-Mn-Si-Cr-Ni shape memory alloy with ultrahigh mechanical properties and large recovery strain by laser powder bed fusion

This work systematically studied the effect of volumetric energy density E on the densification, microstructures, tensile mechanical properties, and shape memory performance of a Fe-Mn-Si-Cr-Ni shape memory alloy (SMA) fabricated by laser powder bed fusion (L-PBF). An E of 90–265 J/mm3 is suggested to fabricate the Fe-Mn-Si-Cr-Ni SMA with minor metallurgical defects and a high relative density of above 99%. The increase in E can promote the formation of the primary γ austenite and the solid phase transformation from the primary δ ferrite to the γ austenite, which helps to achieve a nearly complete γ austenitic microstructure. The increase in E also contributes to fabricating the Fe-Mn-Si-Cr-Ni SMA with superior comprehensive mechanical properties and shape memory performance by L-PBF. The Fe-Mn-Si-Cr-Ni SMA with a combination of good ductility of around 30%, high yield strength of above 480 MPa, an ultrahigh ultimate tensile strength of above 1 GPa, and large recovery strain of about 6% was manufactured by L-PBF under a high E of 222–250 J/mm3. The good shape memory effect, excellent comprehensive mechanical properties, and low cost of Fe-Mn-Si-Cr-Ni SMAs, as well as the outstanding ability to fabricate complex structures of L-PBF technology, provide a solid foundation for the design and fabrication of novel intelligent structures.

A novel strategy for preparing high-performance powder metallurgical low alloy ultrahigh strength steel

In this study, a combined process of hot isostatic pressing and hot rolling (HIP-rolling) is developed to prepare high-performance powder metallurgical (PM) low alloy ultrahigh strength steel. The HIP-rolled 30CrMnSiNi2A steel achieves ultrahigh ultimate tensile strength of 1823.6 MPa, high elongation of 17.6% and superior impact energy of 29.4 J. The formation of lower bainite/martensite duplex structure, the refinement of prior austenite grains and blocks, and the disruption of prior particle boundaries are the critical factors to achieve the excellent strength-toughness balance. This study provides a novel insight for the development and application of PM low alloy ultrahigh strength steel.

Ultrahigh tensile strength achieved in a lightweight medium Mn steel via prominent work hardening

We develop a new ultrastrong medium Mn steel with a density reduced to 7.39 g cm–3. It has a novel tri-phase microstructure comprising a hierarchical martensitic matrix (α’), dispersed ultra-fine-retained austenite grains (γ), and both compressed and {200} oriented δ-ferrite lamellas, the latter's formation is due to the alloying of high Al and Si contents for reducing density. As a result, both ultrahigh ultimate tensile strength of 2.1 GPa and good ductility of 16% are achieved after an extraordinary plastic strain hardening increment of about 1.4 GPa. The in-situ synchrotron-based high-energy (HE) X-ray diffraction (XRD) examinations during the tensile deformation revealed that the initial presence of residual compressive stress in δ-ferrite could increase the stress required to initiate the plastic tensile deformation of the specimen, leading to the isolated δ-ferrite lamellas mostly deformed elastically to coordinate the plastic deformation of the martensitic matrix during yielding. During the plastic deformation, the gradual release of residual compressive stress in δ and α’, the dislocation multiplication in all the three phases and the successive γ-to-α’ transformation all contribute to such a prominent work hardening increment. This study facilitates the development of novel strategies for fabricating ultrastrong but light steels.

A novel maraging stainless steel ultra-high-strengthened by multi-nanoprecipitations

A novel ultra-high strength maraging stainless steel with a chemical composition of Fe-11.5Cr-8.5Co-8.0Ni-5.0Mo-1.2Al-0.01C (in wt.%) has been developed. It utilizes a unique combination of nano scale intermetallic precipitates of Laves, β-NiAl, and sigma phases to achieve an ultra-high ultimate tensile strength up to 3.15 GPa, together with a balanced ductility and uniform elongation of about 2.74% and 2.05%, respectively. Maximizing the austenite content in the as-hot-rolled steel before cold-rolling and ageing treatments is essential to remove work-hardening behaviour and obtain an ultra-high strength without uniform elongation loss of the maraging steel. It is found that precipitation hardening sharply peaks at the ageing temperature of 525 °C for 3.5 h, which is mainly due to the peak strengthening effect of the net-like sigma phase through its transcrystalline fracture during tensile deformation.

Tensile properties and deformation mechanisms of a new Ni–Co base superalloy from room temperature up to 750 °C

In this article, we developed a new Ni–Co base superalloy with excellent mechanical properties in the temperature region from room temperature to 750 °C. The yield and tensile strengths of the alloy at room temperature are ∼1212 MPa and ∼1638 MPa, respectively, and they can still reach ∼1077 MPa and ∼1233 MPa at 750 °C, maintaining a good intermediate temperature strength. Microstructure characterizations show that the plastic deformation is mainly dominated by anti-phase boundary (APB)-coupled dislocation pair shearing γ′ precipitates at room temperature. With increasing the temperature, although the dislocation pair shearing still dominates, stacking fault (SF) shearing and nanotwinning also appears and contributes minor to the plastic deformation. The interactions among dislocations, SFs and nanotwins finally results in the decent working hardening ability even at such a high temperature up to 750 °C, which in turn gives rise to the ultrahigh ultimate tensile strength of the Ni–Co base superalloy.

Achieving high tensile strength-ductility synergy of a fully-lamellar structured near alpha titanium alloy at extra-low temperatures

The previous study has indicated that a near alpha titanium alloy of an equiaxed microstructure could hardly exhibit a desirable ductility at 20 K. This study aimed at achieving a promising balance of superhigh strength and excellent ductility of a Ti−3Al−3Mo−3Zr (wt%) alloy in cryogenic temperature field. Temperature dependence of tensile properties and deformation behavior was investigated systematically. It was found that the ultimate tensile strength (UTS) and elongation-to-fracture (EI) jumped from 730 MPa and 19.0% at 298 K to 1300 MPa and 23.0% at 77 K, respectively. Ultrahigh UTS up to 1600 MPa and an acceptable EI of 13.5% were achieved at 20 K. The ultrahigh UTS at 77 and 20 K was considered to be attributed to the sharp increase of CRSS of slip and the Hall-Petch effect of {101̅2}< 101̅1̅> twinning. The enhanced ductility at 77 K was owing to the improved strain hardening ability from large-scale twinning and prismatic and basal slips. Besides, a serrated plastic flow took place at 20 K, which was essentially because the intermittent start of twinning brought about alternate stress jump and cliff-like drop. A fully-lamellar microstructure is suggested to synchronously enhance the strength and ductility of a near-alpha titanium alloy at extra-low temperatures.

Achieving ultra-high strength in a face-centered-cubic FeCrCoNi high entropy alloy through dense nanotwins bundles structure prepared by cryo-rolling

High/medium-entropy alloys (HEAs/MEAs) with simple single-phase face-centered-cubic (fcc) structures have exceptional tensile ductility and outstanding toughness, but their room-temperature strengths are moderate. Here we introduced a mixed nanostructure, composed of high density nano-scale twins in the form of bundles and nanograins in shear bands, in a single-phase fcc FeCrCoNi HEA by means of cryo-rolling at liquid nitrogen temperature (LNT), which result in a substantial enhancement of tensile strength. The as-prepared nanostructured FeCrCoNi HEA exhibits an ultra-high ultimate tensile strength of ∼1.8 GPa, an elongation-to-failure of ∼10%. The ultra-high strength originates mainly from the effective blockage of dislocation motion by the ultra-high density of internal twin and grain boundaries. The microstructural evolution and formation mechanism of the mixed nanostructure in FeCrCoNi HEA were investigated in detail by transmission electron microscopic characterization.

A high-strength Mg-8Zn-1Mn-3Sn-1.2Gd alloy with fine MgSnGd particles by Dy modification

In the current work, we successfully prepared Mg-8Zn-1Mn-3Sn-1.2Gd-0.2Dy alloy with an excellent combination of ultimate tensile strength and ductility. The mechanism of the Dy-modified MgSnGd phase and its effect on the microstructure and mechanical properties of as-cast and as-extruded alloy were systematically investigated. Experimental results reveal that a new phase MgSn (Gd, Dy) is formed with Dy addition to Mg-8Zn-1Mn-3Sn-1.2Gd alloy, MgSn (Gd, Dy) phase can act as an effective heterogeneous nucleation site of MgSnGd phase. Meanwhile, the addition of Dy consumes Sn and Gd atoms, reducing the enrichment of solute atoms and inhibiting the MgSnGd phase's growth. The Dy addition can effectively promote the dynamic recrystallization process due to the combined effects of the refined grain structure of as-cast alloy and the particle-stimulated nucleation effect caused by dispersed MgSnGd phase. The alloy exhibits an excellent combination of high strength and ductility with the ultimate tensile strength of 384 MPa and an elongation of 14.5%. The fine-grained structure, the uniformly distributed MgSnGd particle, and MgSn (Gd, Dy) nanoparticles are mainly responsible for the ultra-high ultimate tensile strength. The high ductility is due to the fine-grained structure, appropriate decrease of dislocation density, and dynamic recrystallization.

Two-dimensional tetrahexagonal CX2 ( X = P, As, Sb) semiconductors for photocatalytic water splitting under visible light

In this paper, we introduce a family of two-dimensional group-V carbides with an ordered sequence of tetragons and hexagons (th-$\mathrm{C}{X}_{2}$, where $X=\text{P}$, As, and Sb). We demonstrate that th-$\mathrm{C}{X}_{2}$ monolayers exhibit robust energetic, dynamical, thermal, and mechanical stability. Our calculations show that the intrinsic structural anisotropy of the th-$\mathrm{C}{X}_{2}$ family induces strongly anisotropic mechanical, electronic, and optical behavior. These monolayers offer ultrahigh ultimate tensile strength, comparable with that of graphene, making them suitable for strain engineering of electronic and optical properties. They are semiconductors in nature, where th-${\mathrm{CP}}_{2}$, th-${\mathrm{CAs}}_{2}$, and th-${\mathrm{CSb}}_{2}$ possess quasidirect, direct, and indirect band gaps, respectively. The band gaps of th-${\mathrm{CP}}_{2}$ and th-${\mathrm{CAs}}_{2}$ are wide enough to provide the photogenerated energy required for the splitting of water. Besides, the positions of band edges are in alignment with the water oxidation and reduction potentials. For th-${\mathrm{CSb}}_{2}$, however, the suitable width of the band gap and the appropriate band edge positions for photocatalytic water splitting are achieved by strain engineering. Both indirect-to-direct and direct-to-indirect band gap transitions can be induced in th-$\mathrm{C}{X}_{2}$ compounds through strain engineering. The th-$\mathrm{C}{X}_{2}$ monolayers offer anisotropic high charge carrier mobility, which prolongs the average lifetime of charge carrier drift. They have good optical absorption ($\ensuremath{\sim}{10}^{5}$ ${\mathrm{cm}}^{\ensuremath{-}1}$) in the visible and ultraviolet regions of the light spectrum. $G{W}_{0}+$BSE (Bethe-Salpeter equation) calculations reveal that they exhibit strong excitonic effects where the first bright excitonic binding energy is calculated as 0.27, 0.52, and 0.22 eV for th-${\mathrm{CP}}_{2}$, th-${\mathrm{CAs}}_{2}$, and th-${\mathrm{CSb}}_{2}$, respectively. Having all these features in one package, the th-$\mathrm{C}{X}_{2}$ monolayers are among the best candidates for high-performance photocatalytic water splitting.

The martensitic crystallography and strengthening mechanisms of ultra-high strength rare earth H13 steel

Advanced die manufacture demands hot work die steels with superior strength. Unfortunately, due to the rare understanding of the crystallographic structures and strengthening mechanisms of H13 steel, the contradictory between ultra-high strength and low ductility remains inevitably as far as authors known. In this work, we developed a strategy combining rare earth addition, electroslag remelting and pre-tempering treatment, and prepared rare earth (Re) H13 steel with ultra-high ultimate tensile strength up to 2 gigapascals (GPa) and good ductility. The Re H13 steel underwent pre-tempering treatment exhibited hardness of ca. 53.6 HRC, ultimate tensile strength of ca. 2029 MPa, yield strength of ca. 1654 MPa, total elongation of ca. 9.3% and impact energy of ca. 16.0 J (superior grade of NADCA#207–2003 standard), respectively. The good ductility of Re H13 steel mainly attributed to high density of high angle grain boundaries (45° <) of ca. 1.45 μm−1, which derived from high length fraction of V1/V2 inter-variant boundaries (66.9%) by quenching, as well as coarsen sub-grains and variants refinement by subsequent tempering. The dislocation and carbide precipitates have the dominant role in controlling the strengthening of tempered Re H13 steel. The ultra-high strength of Re H13 steel mainly attributed to its high dislocation density (5.72 × 1014 m−2) and high carbide precipitates density (10.1 μm−2), which raised by 73.3% and 21.7% compared to Re H13 steel treated by conventional twice tempering (600 °C) process. The present work not only reveals the strengthening mechanisms of ultra-high strength Re H13 steel, but also characterizes the contributing microstructure feature to its good ductility.

Enhanced mechanical properties by retained austenite in medium–carbon Si-rich microalloyed steel treated by quenching–tempering, austempering and austempering–tempering processes

The microstructure evolution and mechanical properties of a designed 0.56C-1.48Si-0.70Mn-0.71Cr-0.148V-0.011Nb (wt.%) steel subjected to three heat treatments including quenching–tempering, austempering, and austempering–tempering have been investigated. In the quenching–tempering sample, the microstructure of the steel consisted of tempered martensite and a small amount of retained austenite (~8 vol%) with 1.3 wt% C. In the austempering sample, the microstructure contained martensite/bainite laths and adequate amount of retained austenite (~15 vol%) with 1.33 wt% C. Subsequent tempering treatment promoted MC carbides to form and retained austenite to decompose, respectively. Resulting in decrease in the retained austenite amount (~10 vol%) and C concentration (~1.24 wt%). The carbon distribution indicated the stability of the C-rich area along prior austenite grain boundary is higher than that between the martensite/bainite laths. As a result, the present steel shown an ultrahigh ultimate tensile strength (>2200 MPa) and an excellent total elongation (~15%) after austempering treatment. Also, the impact toughness increases from ~12.5 J (quenching–tempering) to ~16 J (austempering) and ~17.5 J (austempering–tempering). As a result of transformation-induced plasticity (TRIP) effect, the austempering sample had the highest values of strain hardening rate and strain hardening exponent in the uniform strain stage and necking stage, thus it obtained a maximum uniform true strain of ~0.087. In addition, the crack source analysis of the three samples all shown ductile dimpled fracture while crack propagation presented as a quasi-cleavage fracture.

Ultrafine-grained Mg–Zn–Yb–Zr alloy with simultaneously improved strength and ductility processed by axisymmetric hot extrusion

The evolution of microstructure and mechanical properties of Mg–6.0 Zn–2.0 Yb–0.5 Zr alloy during axisymmetric hot extrusion was tracked. The initial bimodal-grained sample with most nanoprecipitates presented an ultra-high ultimate tensile strength (UTS) of ~436 MPa and a lower elongation (EL) of ~14.1% along the extrusion direction (ED), while the fully recrystallized ultrafine-grained (UG) sample with less precipitates exhibited a favorable balance in UTS and EL of ~393 MPa and ~19.1%, respectively. The Mg–Zn–Yb thermostable nanoprecipitates present in the alloy improved its strength, and the tilted weak texture that was rarely observed in the axisymmetric extrusion contributed to the ductility enhancement. The present work is likely to provide the fundamental insight into the underlying mechanisms of achieving the strength-ductility synergy via precipitation and texture tailoring in a newly developed Yb-alloyed Mg alloy with conventional and readily available processing technology.

Probing Nanoscale Phase Separation at Atomic Resolution within β-Type Ti-Mn Alloy: A Potential Candidate for Biomedical Implants.

Biocompatible β-type Ti alloys with high ultimate tensile strength (UTS) and yield strength are potential candidates for certain orthopedic and cardiovascular implants. Aiming for these applications, Ti alloy with 14 wt % Mn (Ti-14 Mn) as β-stabilizer was processed through thermomechanical treatment along with solutionizing and quenching, followed by 95% cold rolling, which resulted in ultrahigh UTS and yield strength. 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolimbromide assay with different cell lines suggests efficient cell growth on alloy surface without compromising biocompatibility. Cell adhesion and spreading assay show that cells are not only able to attach to the alloy surface but also able to spread and grow with normal morphology, which projects this material as a potential candidate for biomedical application. Previous studies on binary β-type Ti alloy systems treated with the above-mentioned processing route confirm the presence of nanoscale phase separation, which enhances its mechanical properties. To discover the same phenomena in the alloy of the present study, bright-field and high-resolution transmission electron microscopy (HRTEM) imaging experiments were performed and nanoscale contrast-modulated lamella regions were observed. Geometrical phase analysis on complex-valued exit wave, reconstructed using focal series HRTEM images, demonstrates that the lamella is a result of d-spacing modulation. Ab initio calculation indicates that d-spacing modulation with the same crystal structure occurs due to composition modulation and was proved by scanning transmission electron microscopy imaging coupled with quantitative energy-dispersive X-ray spectroscopy. Correlating contrast, strain, and composition modulation confirms nanoscale phase separation, which is the first report of this phenomenon in Ti-Mn alloy system.

Ageing behavior and mechanisms of strengthening and toughening of ultrahigh-strength Mg-Gd-Y-Zn-Mn alloy

The ageing behavior of as-extruded Mg-1.5Gd-1.3Y-0.6Zn-0.6Mn (at%) alloy was investigated. The strength and ductility are simultaneously improved during ageing at the peak hardness platform. The alloy aged for 100 h exhibits ultrahigh ultimate tensile strength (UTS) of 538 MPa and good elongation to failure (EL) of 13.1%.

Microstructure evolution and mechanical properties of an ultrahigh strength Al-Zn-Mg-Cu-Zr-Sc (7055) alloy processed by modified powder hot extrusion with post aging

A modified powder hot extrusion including gas atomization, pre-compaction and hot extrusion was used to fabricate an ultrahigh strength Al-Zn-Mg-Cu-Zr-Sc (7055) alloy. The results reveal that a homogeneous microstructure containing fine grains and tiny second phases is formed after extrusion. The solution-treated alloy aged at 393 K for 24 h achieves peak hardness of 177 HB due to the common effect of GPI zone and η′ phase. The peak-aged alloy exhibits an ultrahigh ultimate tensile strength of 734 MPa and a good elongation at fracture of 9.8%, which is mainly attributed to fine grains and high-density nanoscale second phases (GP, η′, and Al3(Sc/Zr)). Micropore aggregation fracture is the main fracture mechanism in all the tested alloys states. The cracking or debonding of coarse second phases is the main cause of the limited strength of as-extruded alloy, while the coarse phases and PFZs at the grain boundaries are responsible for the decrease in the elongation of peak-aged sample. Compared with the 7055 alloys fabricated by other techniques, it is suggested that this modified powder hot extrusion may be an effective approach to develop high strength Al alloys.