Orowan Strengthening Research Articles

Enhanced mechanical properties of dispersed carbide-strengthened CrFeNi-based medium entropy alloys prepared via powder metallurgy

In this study, a set of CrFeNi -based medium-entropy alloys (MEAs) with varying carbon contents were prepared by spark plasm sintering (SPS) using atomized alloy powders as raw material. The microstructures of powders and as-sintered alloys were characterized using ECCI and EBSD. The mechanical properties of as-sintered alloys were tested and the strengthening mechanical were discussed. The results showed that the microstructures of the CrFeNi gas atomized powder and sintered alloy were both single FCC phase in an equiaxed state. However, the matrix grains of powder with carbon addition were mostly dendritic, and few eutectic carbides could be observed between matrix grains. Compared with the CrFeNi MEA, the addition of 8 at. % C led to an increase in the yield strength and tensile strength from 395 MPa to 630 MPa–590 MPa and 990 MPa, respectively. Orowan strengthening and grain refinement resulting micro/nano carbides are responsible for the improvement in mechanical properties.

Enhancing strength and ductility of Nb alloy via Y addition by vacuum electromagnetic levitation melting under oxygen carrier route

Niobium (Nb) is considered as candidate material for heat pipe in space nuclear reactors due to high melting point, low density, excellent compatibility with alkali liquid metals, irradiation resistance, workability and welding performance, but low strength restricts it's engineering application. In this work, yttrium (Y) was introduced into Nb matrix to achieve solution strengthening from Y atoms and dispersion strengthening from yttrium oxides. The latter one was realized by oxygen carrier route and vacuum electromagnetic levitation melting technique. Finally, one Nb521 (Nb-5.0 wt%W-1.7 wt%Mo-1.0 wt%Zr-0.07 wt%C) and four kinds of Nb521-xY (x = 0.1, 0.2 0.3 and 0.4 wt%) alloys were prepared. TEM characterization indicated that 80 nm Y2O3 particles were formed in Nb521-0.1Y, which exhibited the highest yield strength of 673 MPa, ultimate tensile strength of 740 MPa as well as larger elongation of 12.8%. Moreover, the solution strengthening of Y atoms and Orowan strengthening of yttrium oxides were evaluated quantitatively.

Enhanced plastic deformation ability of copper matrix composites through synergistic strengthening of nano-Al2O3 and Cr particles

The commercial application of Al2O3/Cu composites (ODS copper) with high Al2O3 content is consistently restricted by their plastic deformability. In order to synergistically improve the plastic deformability of Al2O3/Cu composites, Al2O3/Cu–Cr composites with different Cr contents are prepared by internal oxidation combined with heat treatment by replacing part of the Al2O3 particles with Cr phases heat treatment. The effects of Cr content on the microstructure and plastic deformability of Al2O3/Cu–Cr composites are investigated. It is found that the nano-Al2O3 (8 nm) and Cr (25 nm) particles are uniformly distributed in the copper matrix, and both reach a semi-congruent interface with copper matrix. Meanwhile, the copper matrix undergoes a transition from a [111]Cu hard orientation to a [100]Cu soft orientation, and the increase in Cr content leads to a more pronounced degree of recrystallization in the Al2O3/Cu–Cr composites. The results of geometric phase analysis (GPA) show that the coordinated deformability between Cr and Cu is better than that between Al2O3 and Cu. The elongation of 2.5Al2O3/Cu-0.3Cr composite increased to 24.48 % from 22.47 % of the Cr-free 2.8Al2O3/Cu composite. The results of tensile strength calculations show that the tensile strength of Al2O3/Cu–Cr composites is mainly dominated by matrix strengthening and Orowan strengthening induced by Al2O3 particles, while grain strengthening, dislocation strengthening, and Orowan strengthening induced by Cr particles play a secondary role. The correlation coefficient (R2) is 0.95 after fitting the experimental and theoretical values of tensile strength of Al2O3/Cu–Cr composites.

Simultaneously enhanced electro-mechanical properties of CNTs/Cu-20wt.%Mo composite material by regulating interface with Mo2C nanoparticles

The Mo2C@CNTs/Cu-20wt.%Mo composite materials with outstanding mechanical properties and electrical conductivity were prepared via the combination of mechanical wet-mixing, ball-milling and spark plasma sintering technology. By regulating the morphology and content of Mo2C decorated on CNTs, the Mo2C nanoparticles are anchored on CNTs and well bonded with the matrix, resulting the good interfacial bonding in the composite material. The Cu-20wt.%Mo composite material reinforced by 0.2wt.%Mo2C@CNTs exhibits a yield strength of 342.19 MPa and an ultimate tensile strength of 390.37 MPa, which are respectively increased by 23.13 % and 20.34 % as compared to the Cu-20wt.%Mo. Besides, the electrical conductivity of the 0.2wt.%Mo2C@CNTs/Cu-20wt.%Mo composite material is also improved by 6.89 %. Furthermore, the strengthening effect of Mo2C@CNTs/Cu-20wt.%Mo composite material can be attributed to the contribution of Mo2C nanoparticles, which not only enhance the CNTs load transfer strengthening but also promote the dislocation strengthening and Orowan strengthening.

Superstrengthening effect of beyond-solid-solution laser powder bed fused WE43 magnesium alloy triggered by direct aging treatment

Laser powder bed fusion (LPBF) technology exhibits the potential to develop magnesium alloys as lightweight, load-bearing components in critical industries such as aerospace and automotive. This study investigated the effects of various direct aging treatments on the microstructural evolution and mechanical properties of the beyond-solid-solution WE43 magnesium alloy fabricated via LPBF. The results show that the limited kinetic conditions provided by aging at 175°C lead to the decomposition of the beyond-solid-solution to form the β' metastable phase. The original β1 phase transformed to β' and β'' along the direction of least resistance. These nanoscale coherent phases increased the stored deformation energy, acting as nucleation sites for dynamic recrystallization and stimulating the formation of low-angle grain boundaries. This contributed to segmenting grains into multiple zones and subcrystals. Therefore, after aging at 175°C for 64 h, the grain size decreased from 3.39 to 1.96 μm. Meanwhile, the ultimate tensile strength (UTS) increased from 313 to 353 MPa, yield strength (YS) from 236 to 297 MPa, and elongation (EL) from 7.6 % to 12.4 %. Additionally, the aging treatment at 175°C for 128 h shifted the dominant strengthening mechanism from grain boundary strengthening to Orowan strengthening. As a result, the strengths of the alloy aged at 175°C/128 h exceeded the as-built alloy by 53 and 80 MPa for UTS and YS, respectively.

Semantic integration of diverse data in materials science: Assessing Orowan strengthening

This study applies Semantic Web technologies to advance Materials Science and Engineering (MSE) through the integration of diverse datasets. Focusing on a 2000 series age-hardenable aluminum alloy, we correlate mechanical and microstructural properties derived from tensile tests and dark-field transmission electron microscopy across varied aging times. An expandable knowledge graph, constructed using the Tensile Test and Precipitate Geometry Ontologies aligned with the PMD Core Ontology, facilitates this integration. This approach adheres to FAIR principles and enables sophisticated analysis via SPARQL queries, revealing correlations consistent with the Orowan mechanism. The study highlights the potential of semantic data integration in MSE, offering a new approach for data-centric research and enhanced analytical capabilities.

Investigating the impact of cobalt incorporation on the transformation of Cu6Sn5 layer to (Cu, Co)6Sn5: Microstructural and mechanical insights

In this study, cobalt (Co) particles were incorporated as reinforcing agents into the Sn58Bi solder. The solderability of the solder and the strength of the solder joints were investigated. The results indicated that adding Co particles did not alter the low melting point characteristics of the Sn58Bi solder, yet its undercooling was reduced, and the wettability was enhanced. In the Sn58Bi/Cu solder joint, adding Co led to forming free (Cu, Co)6Sn5 intermetallic compound (IMC) and generating the CoSn2 phase through microalloying. The interfacial IMC was gradually transformed from a fan-shaped Cu6Sn5 to a flatter layer-like (Cu, Co)6Sn5 IMC, eventually exhibiting a coral-like structure with increased Co content. Adding Co particles increased the thickness of the IMC layer, but at low levels, the Co could refine the IMC grains. Simultaneously, implementing grain refinement and Orowan strengthening resulted in heightened microhardness and shear strength. In the shear test, the fracture of solder joints predominantly transpired within the solder matrix. Excessive Co particles were prone to aggregating within the solder, forming irregular block-shaped (Cu, Co)6Sn5. Concurrently, the coral-like IMC at the interface led to a decline in the mechanical performance of the solder joints, with some interfacial IMC being exposed in the fracture region.

Unveiling the strengthening and toughening effects of copper-coated carbon nanotubes for the AlLiCu alloy matrix composite

Carbon nanotubes (CNTs) reinforced Al–Li–Cu alloy matrix composite is a promising candidate for the lightweight structural materials demanded in advanced industrial areas such as aerospace. However, how to fully exploit the combined strengthening effects of CNTs and precipitates of the Al–Li–Cu matrix is still an open issue. In the present study, the Cu coating was firstly precoated on CNTs before fabricating CNTs reinforced Al–Li–Cu alloy matrix composite. Benefiting from the Cu coating, the improved CNTs dispersion and Al-CNTs interfacial bonding was achieved, and the precipitation of Al2Cu, Al2CuLi, and Al3Li was enhanced in the AlLiCu alloy matrix, resulting in the enhanced strength-ductility synergy for Cu-coated CNTs reinforced AlLiCu alloy matrix composite. Moreover, strengthening and toughening mechanisms analyzation reveals that the Orowan strengthening of CNTs and precipitates, as well as load transfer strengthening of CNTs contribute mostly to the improved strength, while the increased ductility dominantly derives from the improved CNTs dispersion and Al-CNTs interfacial bonding, and the formation of low-density dislocation nanoregion (LDDN) in the interface area. This study not only opens up a new way for developing the AlLiCu alloy matrix composite reinforced by Cu-coated CNTs but also guides the microstructure regulation of other Al alloy matrix composites.

Effect of Deep Cryogenic Aging Treatment on Microstructure and Mechanical Properties of Selective Laser-Melted AlSi10Mg Alloy

Deep cryogenic aging (DCA) is a newly developed heat treatment technique for additive-manufactured metallic materials to reduce residual stress and improve their mechanical properties. In this study, AlSi10Mg alloy samples fabricated by selective laser melting were deep-cryogenic-treated at −160 °C and subsequently aged at 160 °C. Phase and microstructural analyses were conducted using X-ray diffraction, optical microscopy, scanning electron microscopy, and transmission electron microscopy, while the mechanical properties were evaluated through microhardness and tensile testing at room temperature. The results indicated that the DCA treatment did not have an effect on the morphology of the melt pools. However, it facilitated the formation of atomic clusters and nanoscale Si and β′ phases, as well as accelerating the coarsening of grains and the ripening of the eutectic Si phase. After DCA treatment, the mass fraction of the Si phase experienced an increase from 4.4% to 7.2%. Concurrently, the volume fraction of the precipitated secondary phases elevated to 5.1%. The microhardness was enhanced to 147 HV, and the ultimate tensile strength and yield strength achieved 495 MPa and 345 MPa, respectively, with an elongation of 7.5%. In comparison to the as-built specimen, the microhardness, ultimate tensile strength, and yield strength increased by 11.4%, 3.1%, and 19.0%, respectively. The improvement in mechanical properties is primarily attributed to the Orowan strengthening mechanism induced by the secondary phases.

Microstructural evolution and mechanisms affecting the mechanical properties of wire arc additively manufactured Al-Zn-Mg-Cu alloy reinforced with high-entropy alloy particles

The mechanical properties of Al-Zn-Mg-Cu alloys produced via wire arc additive manufacturing (WAAM) are often weakened by the presence of continuous and coarse precipitated phases, which significantly limits their practical applications. In this study, high-entropy alloy (HEA) particles were incorporated into Al-Zn-Mg-Cu alloy during the WAAM process, which inhibits the continuity of precipitated phase, and the mechanism of microstructure evolution and macroscopic mechanical properties optimization of the components are explored. The results show that HEA particles promote grain refinement, and disrupt the formation of continuous precipitated phase along the grain boundary by generating plenty of fine spot-like precipitated phases, thus inhibiting grain boundary segregation. The spot-like precipitated phases are connected via a slender second-phase-band. The primary precipitates include the metastable η', stable η, and T phases, and the diffusion of solute atoms forms the Al3Ni and Al3(Ni, Cu)2 phases. The tensile strength increases from 247.4±5.9 MPa to 326.2±19.7 MPa in the horizontal direction and from 273.0±13.7 MPa to 335.4±11.1 MPa in the vertical direction, which correspond to increases of 31.9 % and 22.9 % respectively. The enhancement of mechanical properties is mainly attributed to Hall-Petch, Orowan, load-transfer, solid-solution and dislocation strengthening mechanisms. Only slight variation occurred in the elongation, the increased number of fine spot-like precipitated phases and grain boundaries hinder the crack propagation, while the increased number of pores facilitates the crack propagation, and these effects almost balance each other out in competition. These findings are expected to provide new insights into the microstructure optimization of WAAM components, thereby meeting more practical applications.

Microstructure evolution and properties of Mg-9Gd-0.8Al alloy with lamellar phase during extrusion at different temperatures

To clarify the evolution of lamellar phases in the initial microstructure of the Mg-9Gd-0.8Al alloy during the extrusion process and the effect of lamellar phases on the dynamic recrystallization of the extruded Mg alloy, the solid solution treated Mg-9Gd-0.8Al (SS10) alloy, was extruded at different temperatures (380, 400, and 450 °C). With the extrusion temperature increasing, the average size of dynamically recrystallized (DRXed) grains and the second phases decreases firstly and then increases. However, the volume fraction of DRXed grains shows an opposite trend, while the amount of the second phases consistently decreases. The as-extruded SS10 alloy demonstrates superior mechanical properties when extruded at 400 °C, with a yield strength (YS) of 240 MPa, ultimate tensile strength (UTS) of 298 MPa, and elongation (EL) of 19.3%. The alloy achieves enhanced strength through grain boundary strengthening, dislocation strengthening, and Orowan strengthening. Moreover, the presence of DRXed grains with a weak texture plays a significant role in the improvement of the ductility of the alloy.

Effect of ageing temperature on the microstructural evolution and mechanical properties in M2C and NiAl co-precipitation secondary hardening ultrahigh-strength steel

A novel cost-effective secondary hardening ultrahigh-strength steel, strengthened by the co-precipitation of M2C and NiAl, was developed. The present study systematically investigated the co-precipitation evolution, austenite reversion, and mechanisms of strengthening and toughening at different ageing temperatures. As the ageing temperature increased, the quenched microstructure underwent various transformations, including precipitation and dissolution of cementite, nucleation and coarsening of M2C and NiAl nanoparticles, as well as reversion of austenite. At ageing temperatures of 427 °C and 454 °C, a small amount of cementite was present in the martensite matrix, and M2C and NiAl precipitates started to form, resulting in low strength and poor toughness. At 482 °C, the peak-ageing stage was reached, achieving a maximum yield strength of 1875 ± 4 MPa and an ultimate tensile strength of 2185 ± 3 MPa. This strength is primarily attributed to shear strengthening of NiAl particles and Orowan strengthening of M2C carbides. Additionally, the complete dissolution of cementite at this stage improved toughness. As the ageing temperature increased to 510 °C and 538 °C, the strength decreased due to coarsening of M2C, while the toughness improved as a result of film austenite reversion and enhanced dislocations bypassing around the M2C carbides.

Laser powder bed fusion to fabricate high-entropy alloy FeCoCrNiMo0.5 with excellent high-temperature strength and ductility

FeCoCrNi, a high-entropy alloy fabricated by laser powder bed fusion, has excellent room-temperature mechanical properties but poor high-temperature mechanical performance. To expand the application of FeCoCrNi, in this study, we added Mo to form σ precipitates, which improved the high-temperature mechanical properties of the alloy via Orowan strengthening. We also elucidated the main deformation mechanism of FeCoCrNiMo0.5, involving the transformation of the deformational mode from dislocation-based motion to twinning deformation.

Towards high performance Al–Si–Fe alloy castings via rheo-diecasting: Effect of injection velocity and heat treatment on microstructure evolution and property

The mechanical properties and thermal conductivity of Al–Si–Fe castings must meet high requirements in the automobile, aerospace, and communication fields. Traditional high-pressure diecasting (HPDC) castings often have dendritic structures and pore defects that deteriorate their overall performance. Therefore, an advanced rheo-diecasting (RDC) technique assisted by a vibrating contraction sloping plate was proposed to address this problem. However, the process optimization strategy, microstructural evolution, and performance improvement mechanisms remain unclear. The influence of the injection velocity on the microstructure, mechanical properties, and thermal conductivity of the RDC tensile specimens was first investigated. A high-performance cover plate was fabricated via RDC using an optimized injection velocity. The results showed that when the injection velocity increased to 2.8 m/s, the porosity decreased to a minimum value, and the mechanical performance and thermal conductivity of the RDC tensile specimens reached their maximum values. Furthermore, spherical eutectic Si phases and nanosized Mg2Si precipitates for the RDC cover plate were observed after T6 heat treatment, which further improved the mechanical properties and thermal conductivity owing to Orowan strengthening and decreased lattice distortion, respectively. The ultimate tensile strength, yield strength, elongation, and thermal conductivity for the RDC cover plate were 358.2 MPa, 279.9 MPa, 12.5%, and 180.72 W/(m·K), respectively, which were higher than that of reported similar alloys. From engineering perspectives, this study had the application value for produce of high-quality RDC castings.

An investigation on the effect of heat input to wear behavior and corrosion-cavitation erosion mechanism of Hastelloy C-276 coating by cold metal transfer

Cold metal transfer (CMT) technology based on wire-arc manufacturing has attracted wide attention because of its advantages of high manufacturing efficiency, low heat input (HI) and near-net-shape. In this study, a CMT-Hastelloy C-276 superalloy surface modification coating by optimizing HI is used to solve the problem of premature failure of key over-flow components of stainless steel in marine engineering. When the HI is increased from 269 J/mm to 358 J/mm, the serious cavitation erosion (CE) damage caused by pore defects and excessive residual tensile stress due to excessive low HI of Hastelloy C-276 coating can be avoid, which is attributed to the effective Orowan strengthening and high proportion of low angle grain bounds (LAGBs: 70.2%). In addition, high contents of Cr, Mo and W elements can promote it's passivation film to maintain excellent self-healing ability during CE to provide continuous and stable protection effect (Rct = 75.68 kΩ·cm2) in the 3.5 wt% NaCl artificial seawater. Therefore, even after 10 h-CE, it still maintains the highest corrosion resistance from both of the thermodynamic (Ecorr = −193.5 ± 3.6 mV) and kinetic perspective (Icorr = 69.3 ± 3.1 μA·cm−2) and has the lowest mean depth erosion rates (MDER, 0.94 ± 0.07 μm/h). However, further increase of HI will cause coarsing of grains (89.6 ± 2.7 μm → 342.8 ± 9.7 μm), excessive precipitation of brittle Mo-rich p phase and excessive dilution of elements from the substrate, resulting in changes in the wear mechanism and deterioration of strength and corrosion resistance. Moreover, the potential of zero charge (PZC) measurements and Mott-Schottky (M-S) test confirmed the decreasing trend of the repulsive ability to Cl ions (ΔE = 0.58 V) and the increased ion doping concentration (ND = 5.94 ± 0.02 × 1022 cm−3) of the weakened n-type passivation films. The optimal combination of wear resistance, corrosion resistance and CE resistance of Hastelloy C-276 coating is obtained by regulating HI, which can lay a theoretical foundation for the related production and application of marine engineering.

Effect of aging treatment on microstructure and wear performance of Ni-rich NiTiFe alloy

NiTi-based alloys with high nickel content have been utilized as a novel bearing material because of their exceptional hardness, superior wear resistance and corrosion resistance etc. In this work, microstructure, hardness and wear behavior of (Ni56Ti44)95Fe5 alloy were investigated as a function of aging duration. It is found that with increasing aging duration, Ni4Ti3 phase formed continuously and transformed into Ni3Ti phase in a short time due to the addition of Fe. In this case, the highest hardness (729 HV) and the lowest coefficient of friction (0.611) were obtained in the sample aged at 400 °C for 5 h. The dependence of hardness and wear behavior of (Ni56Ti44)95Fe5 alloy was attributed to the combined effect of Orowan strengthening by nano-sized Ni4Ti3 phase and the soften effect of Ni3Ti phase. The wear behavior of (Ni56Ti44)95Fe5 alloy was governed by the combined mechanism of adhesive wear, abrasive wear and oxidative wear.

Effect of Ti3SiC2 replacing graphite on the microstructure and properties of Cu-Sn matrix composites

A new type of intelligent lubrication functional material, Cu-5Sn/22vol%Cr3C2/16vol%Ti3SiC2 composite, was fabricated by powder metallurgy. The mechanical and tribological properties of Cu-Sn/Cr3C2/Ti3SiC2 composite were studied. Ti3SiC2, as a lubricating component, had a better reinforcing effect than graphite. Compared with Cu-Sn/Cr3C2/Gr composite, Cu-Sn/Cr3C2/Ti3SiC2 composite exhibited a 97% increase in hardness and 144% increase in compressive strength, reaching 223 HV and 821 MPa, respectively. Moreover, Cu-Sn/Cr3C2/Ti3SiC2 composite’s wear rate was lower than those of Cu-Sn/Cr3C2/Gr composite under different loads. The enhancement was ascribed to the Ti3SiC2 particles, which had a well-bonded interface with the matrix and induced a higher Orowan strengthening effect. The studied composites with enhanced mechanical and tribological properties have promising potential for application in bearings and mechanical transmission devices.

Study on microstructure, tensile performance and creep resistance of Al–Mg–Si-Sc-Zr alloy strengthened by Al3(Sc, Zr) nanoprecipitates

In this work, a newly designed Al–Mg–Si-Sc-Zr alloy with both excellent room-temperature tensile performances and high-temperature creep resistance was prepared. The microstructure of Al–Mg–Si matrix alloy was significantly modified by Sc, Zr micro-alloying. The average grain size of Al–Mg–Si-Sc-Zr alloy in as-cast and as-rolled states was 68.3 μm and 7.33 μm respectively, which was far smaller than those of Al–Mg–Si alloy. Numerous Ll2-ordered Al3(Sc, Zr) nanoprecipitates ranging from 20 to 60 nm were generated during heat treatment, and they had a strong coherent interface relation with α-Al matrix. During rolling deformation, a further DRX (dynamic recrystallization) progress happened in Al–Mg–Si-Sc-Zr alloy due to the severe dislocations pile-up caused by Al3(Sc, Zr) nanoprecipitates. The YS (yield strength), UTS (ultimate tensile strength) and EL (elongation) of as-rolled Al–Mg–Si-Sc-Zr alloy at room temperature were 315.2 MPa, 372.3 MPa and 20.1 % respectively, which were increased by 21.9 %, 17.1 % and 41.5 % compared to tensile performances of Al–Mg–Si matrix alloy. An enhanced high-temperature creep resistance was obtained by Al–Mg–Si-Sc-Zr alloy, which was mainly attributed to the outstanding thermal stability possessed by Al3(Sc, Zr) nanoprecipitates. The strengthening mechanisms including grain refinement strengthening and Orowan strengthening were also discussed.

Strength-ductility synergy in a novel carbon nanotube-high entropy alloy co-reinforced aluminum matrix composite

Here we present a novel design strategy for the manufacturing carbon nanotube (CNT)-high entropy alloy (HEA) particles co-reinforced aluminum matrix composites (AMCs) with heterogeneous structures. This strategy involves in situ synthesis of CNTs@HEA hybrid reinforcement. The results demonstrate that the fabricated CNTs@HEA/Al composites have bimodal grain structure and nano-reinforced particle spatial distribution. The dispersion of CNTs within the Al matrix was achieved via the transport of micron-sized HEA particles. Simultaneously, the formation of Al4C3 and Cr7C3 occurred at the HEA/CNTs/Al interface, thereby augmenting the load-bearing capacity of CNTs. The enhanced strength of CNTs@HEA/Al composites is mainly attributed to the synergistic effect of load transfer, back stress strengthening, Orowan strengthening, grain refinements and stacking faults (SFs) strengthening. Moreover, the bimodal grains and SFs of the composite contribute sustained strain hardening, resulting in satisfactory tensile ductility.

Effect of sintering temperature on microstructure and mechanical properties of Ti2AlNb-based composites

Ti2AlNb-based composites are a great choice for achieving high-temperature properties by introducing reinforcement to meet engineering application requirements. In this study, Ti–22Al–25Nb (at.%) alloys and nano-Al2O3/Ti–22Al–25Nb composites were prepared by mechanical alloying (MA) and hot pressing (HP). The effects of sintering temperature on the microstructure and mechanical properties of Ti–22Al–25Nb alloys and Ti2AlNb-based composites were investigated. The sintering temperature effectively regulated the morphology and size of the primary O phase. The addition of Al2O3 particles refined the grain size of the matrix and precipitates, and it induced the phase transformation. When the sintering temperature reached 1350 °C, Ti–22Al–25Nb alloys and Ti2AlNb-based composites obtained a fine and uniform equiaxed microstructure. The hardness and ultimate compressive strength of the composite first increased and then decreased with increasing sintering temperature. Since the addition of Al2O3 particles promoted the precipitation of the ultrafine acicular O phase from the B2 phase, the composite sintered at 1350 °C had the optimal mechanical properties. The hardness of the Ti–22Al–25Nb alloy and Ti2AlNb-based composite was 4.12 GPa and 5.1 GPa, respectively. The ultimate compressive strength of the composite at room temperature (RT) and 650 °C was 2642.3 MPa and 2462.5 MPa, which was 25.8% and 9.6% higher than that of the Ti2AlNb alloy. The strengthening mechanism of the composites mainly includes dispersion strengthening and Orowan strengthening of the nano-Al2O3 particles, as well as precipitation strengthening of the acicular O phase. This study provides a theoretical guidance for designing Ti2AlNb-based composites with excellent high-temperature properties.