Equiaxed Microstructure Research Articles

Meta-structure of amorphous-inspired 65.1Co28.2Cr5.3Mo lattices augmented by artificial intelligence

A hatching-distance-controlled lattice of 65.1Co28.2Cr5.3Mo is additively manufactured via laser powder bed fusion with a couple of periodic and aperiodic arrangements of nodes and struts. Thus, the proposed lattice has an amorphous-inspired structure in the short- and long-range orders. From the structural perspective, an artificial intelligence algorithm is used to effectively align lattices with various hatching distances. Then, the metastable lattice combination exhibits an unexpectedly high specific compression strength that is only slightly below that of a solid structure. From the microstructural perspective, the nodes in the newly designed lattice, where the thermal energy from laser irradiation is mainly concentrated, exhibit an equiaxial microstructure. By contrast, the struts exhibit a columnar microstructure, thereby allowing the thermal energy to pass through the narrow ligaments. The heterogeneous phase differences between the nodal and strut areas explain the strength-deteriorating mechanism, owing to the undesirable multi-phase development in the as-built state. However, solid-solution heat treatment to form a homogeneous phase bestows even higher specific compression strength. Furthermore, electrochemical leaching leads to the formation of nanovesicles on the surface of the microporous lattice system, thereby leading to a large surface area. A more advanced valve cage for use in a power plant is designed by using artificial intelligence both to (i) effectively preserve its mechanical stiffness and (ii) actively dissipate the generated stress through the large surface area provided by the nanovesicles.

Phase Transformation, Microstructural Evolution and Tensile Properties of a TiH2-Based Powder Metallurgy Pure Titanium

Multiple phase transformations were carried out during dehydrogenation process of TiH2-based powder metallurgy. The influence of phase transformation on the microstructure is highly worthy of attention. In situ synchrotron radiation was employed to investigate the phase transformation sequence of TiH2 powder compact during the vacuum sintering process. It was found that a transformation route TiH1.971 → TiH2 + TiH + TiH0.71 + α(H) → TiH + TiH0.71 + α(H) → TiH + TiH0.71 + α(H) + β(H) → α(H) → α took place, resulting in an equiaxed microstructure. Increasing heating rate and avoiding the intense dehydrogenation to retain hydrogen-rich β (β(H)) and TiHx aciculae at the interfaces is found to be a feasible method to fabricate hierarchical α-Ti structures. A fully dense fine martensitic microstructure was produced after fast heating the TiH2 powder compact to 1100 °C and an immediate hot extrusion. Subsequently, by vacuum annealing treatment at 700 °C, composite α/βt lamellar structures were generated and a simultaneously enhanced tensile strength of 746 MPa and excellent elongation to fracture of 33.8% were achieved. It is suggested that adjusting the dehydrogenation reactions of TiH2-based powder metallurgy is conductive to generating hierarchical lamellar structures with a highly promising combination of strength and ductility for pure Ti.

Influence of Equal Channel Angular Pressing and Cyclic Extrusion Compression on the Microstructure Evolution and Mechanical Properties of Pure Aluminum.

The influence of equal channel angular pressing (ECAP) and cyclic extrusion compression (CEC) of Al-1080 on the pressing load, microstructure, and tensile properties was investigated. The pressing peak loads of the CEC were 218.8-265.4% higher than those of the ECAP, with a more complex load behavior in the CEC process. The deformation morphology of the ECAP samples indicates an improvement in the deformation homogeneity with the number of passes. Shear band morphology with a decrease in the shear band width from the center to the outer surface makes up the predominant pattern of the CEC samples. The ECAP samples have 13.9-44% smaller average grain sizes, with 3.8-8.1% higher high-angle grain boundaries (HAGBs) than the CECed samples. The ECAP and CEC processing improve the tensile strength. However, the ECAP sample's tensile strength (UTS) and the proof strength (σ0.2) were 11.5-20.6 and 2.6-16.4% higher than that of CEC, without noticeable differences in elongation. The σ0.2 values were predicted accurately with a deviation range of 1.8-7.3% from the experimental one. The ECAP samples are easy to process under lower loads. Moreover, ECAP samples have an equiaxed grain microstructure with a higher degree of deformation homogeneity and tensile strength.

Large-Size and Ultrahigh Purity Tungsten with Enhanced Physical Properties via Chemical Vapor Deposition.

Conventional powder metallurgy techniques fail to meet the demands for ultrahigh purity tungsten (UHPW) and scalable component sizes required by the semiconductor industry. In this study, ultrahigh purity (99.999998 wt %) large-size tungsten parts, with an adjustable thickness and a diameter of 350 mm, were prepared via a chemical vapor deposition (CVD) method using ultrahigh purity (99.9999 wt %) tungsten hexafluoride (WF6) as the precursor. The microstructure and physical properties of the resulting CVD-UHPW were evaluated and compared with those of powder metallurgy tungsten (PM-W). The results indicate that CVD-UHPW displays a columnar grain microstructure with a lower dislocation density and internal strain, whereas PM-W shows an equiaxed grain microstructure. CVD-UHPW has a density of 19.17 g/cm3, closely matching the theoretical density of tungsten (19.35 g/cm3) and significantly higher than PM-W's density of 18.79 g/cm3. The specific heat capacities of CVD-UHPW, measured from 298 to 1473 K, range from 0.113 to 0.146 J/g·K, similar to PM-W's range of 0.120 to 0.151 J/g·K. CVD-UHPW shows improved electrical and thermal conductivities compared to PM-W, with values ranging from 1.68 × 106 to 1.78 × 107 S/m and 105.7 to 196.4 W/(m·K) from 298 to 1473 K. This study highlights the potential of the CVD method for the large-scale production of ultrahigh purity tungsten parts, emphasizing its significant applicability across various industries.

The effect of annealing on the microstructure and wear performance of laser-clad high-entropy alloy composite coatings for monorail crane braking systems

Laser cladding was utilized to fabricate WC ceramic particle-reinforced CoCrFeMnNi high-entropy alloy (HEA) composite coatings, with an investigation into the influence of annealing heat treatment on the microstructure and wear behavior of the composite coatings. The HEA composite coatings with a WC particle content of 30 wt% primarily consist of a face-centered cubic (FCC) solid solution phase, various M6C carbides with blocky, fishbone, and dendritic morphologies, and incompletely melted WC ceramic particles. The microstructure of the composite coatings remains stable up to a temperature of 570°C. After annealing at 600°C, the microstructure transforms into a typical dendritic morphology with rod-like carbides precipitating from the solid solution and discontinuously distributed in the interdendritic regions. Due to the annealing softening effect, the microhardness of the coating decreases from 488.1 HV0.3 to 443.1 HV0.3. Following annealing at a high temperature of 800°C, recrystallization leads to a refined equiaxed grain microstructure, with precipitated carbides continuously distributed along the grain boundaries, forming a network. The combined effects of precipitation hardening and fine grain strengthening result in an increase in the microhardness of the coating to 568.6 HV0.3 after annealing at 800°C. As the annealing temperature increases, the wear rate of the WC particle-reinforced CoCrFeMnNi HEA composite coatings also increase. The wear mechanism for the unannealed coating is oxidative wear, and the reduction in hardness leads to adhesive phenomena in the coating after annealing at 600°C. The network of carbides reduces the ductility of the HEA and also the toughness of the oxide film, resulting in the highest wear rate for the coating annealed at 800°C, reaching 38.636×10−6 mm3/(N·m). This study provides valuable insights for the fabrication of advanced wear-resistant coatings.

Effect of vibration frequency on mechanical properties and microstructure of metal inert gas welded dissimilar AA5083 and AA6061 aluminum alloy joints

This study explores how the frequency of vibrations affects the physical, mechanical, and residual stress properties in dissimilar metals welding between AA5083 and AA6061. The vibration-assisted welding process involves the application of vibration frequencies; 0 Hz, 10 Hz, 30 Hz, and 50 Hz. Weld joints were then examined for their microstructure, tensile strength and impact strength. They were also examined using X-ray diffraction to quantify surface residual stress. The findings suggest that welding with a 50 Hz vibration frequency produced weld metal characterized by a fine and consistent equiaxed microstructure. This welded joint exhibited exceptional mechanical property, boasting an ultimate tensile strength (UTS) of 197.87 MPa, an elongation of 15.28 %, and an impact strength of 8.10 J (J). Moreover, this welded joint displayed the lowest surface residual stress within the weld metal, measuring at 110.9 MPa. The application of high-frequency vibrations during aluminum welding promotes a more homogeneous mixing of molten metals between AA5083 and AA6061 in the weld metal. These vibrations also result in increased internal pressure within the molten weld metal, causing dissolved gas bubbles like H2, O2, and N2 to break and release.

Machinability of Ti6Al4V Alloy: Tackling Challenges in Milling Operations

This study investigates strategies for improving the 3D milling of Titanium Alloy Grade 5 (Ti6Al4V) by optimizing machining parameters and cutting tool engagement techniques. Ti6Al4V presents significant machining challenges due to its low machinability index (20%), which directly impacts manufacturing efficiency. High temperatures during machining, often exceeding 8820C, lead to phase transformations, creating a harder Beta lamellar equiaxed microstructure. This, coupled with the alloy's poor thermal conductivity, results in heat concentration at the cutting tool interface, accelerating thermo-chemical wear and potentially catastrophic tool failure. This study explores how controlled cooling methods, coupled with appropriate lubrication, can effectively dissipate heat and flush away chips, mitigating the detrimental effects of high temperatures. Furthermore, the selection of cutting tool materials and coatings with high thermal conductivity and chemical inertness, along with aggressive rake angles and higher relief angles, are examined as methods to improve shearing, minimize smearing, and enhance surface quality. By optimizing these parameters, this study aims to provide manufacturers with practical strategies to overcome the challenges of Ti6Al4V machining, ultimately increasing tool life and overall milling efficiency.

Fully Consolidated Deposits from Oxide Dispersion Strengthened and Silicon Steel Powders via Friction Surfacing

Abstract The objective of this work is to study the ability of friction surfacing to deposit metal alloys that are difficult to process with traditional methods. Creep and neutron irradiation resistant oxide dispersion strengthened (ODS) materials cannot be produced via conventional casting route due to insolubility of the oxidic and metallic alloy constituents, causing unintended inhomogeneous oxide dispersion and material behavior. Increasing silicon content of Iron-Silicon (Fe-Si) improves electromagnetic properties but embrittles the material significantly and the fusion based manufacturing methods unable to process this steel. The solid-state nature of the friction surfacing process offers a potential alternative processing route to enable wider usage of difficult to process alloy systems. Both ODS and Fe-Si materials are available in powder forms. While the existing literature in friction surfacing focuses on depositing composites by incorporating small quantities powders through holes in consumable rod, this is a first study that shows a large charge of powder can be converted to a homogeneous fully consolidated deposit in friction surfacing. A novel methodology is used that incorporates the high portion of powder feedstock into hollow consumable friction surfacing rods (up to 35% volume fraction). It was found that fully consolidated deposits can be produced with powder feedstocks using proposed methodology. A recrystallized, homogeneous, equiaxed microstructure was observed in Fe-Si 6.8 wt% and a new generation FeAlOY ODS alloy deposits processed with hollow stainless-steel friction surfacing rods. Both powder and rod material plasticize and deposit without bulk intermixing.

Microstructure evolution in AlSi10Mg alloy fabricated by laser-based directed energy deposition

Investigation of the influence of processing parameters on the microstructure evolution of the melt pool is important for microstructure control in laser-based directed energy deposition (DED-LB) processes. Single-track experiments of DED-LB AlSi10Mg alloy were conducted in this work, processing with two laser powers (900 and 1800 W) at a fixed scanning speed (20 mm/s). The grain morphology was changed from columnar to equiaxed towards the center of each melt pool. Meanwhile, the morphology of the α-Al cells in the grains varied from elongated to equiaxed along the same direction due to the increase of cooling rate. A more equiaxed microstructure can be obtained in the melt pool produced at a larger laser power. The scales of the microstructures and the grain morphologies in the melt pools were in accord with the microstructure selection map and grain morphology selection map in temperature gradient (G)–growth velocity (V) space constructed by solidification models. Since G and V are directly related to laser power and scanning speed, the G–V maps can provide the guidance for processing optimization to tailor microstructures in DED-LB Al–Si alloys based on the temperature field simulations of melt pools.

Machinability of Ti6Al4V Alloy: Tackling Challenges in Milling Operations

This study extensively elaborates the approach towards making ease in 3D milling of Titanium Alloy Grade 5; by adapting the controlled parameters and specific strategies in cutting tool encroachment in milling. Every manufacturer is anxious about the machinability index (20%) of Ti6Al4V, which affects the machining efficiency proportionally. During machining, Phase alteration above the 8820C produces a Beta lamellar equiaxed microstructure, which is hard; also, limited thermal conductivity allows the generated heat towards the cutting tool to lead the Thermo-assisted wear. Higher temperatures also initiated chemically eagerness of Ti6Al4V and reacted with cutting tool edge and escorts towards catastrophic failure. The difficult Machinability demonstrates the detrimental notable effect on the cutting tool's health and follows the Ti6Al4V surface quality. The Cooling methods can flush out chips and frictional heat with ample lubrication, desirably controlling the worse effect of Machinability to some extent blissfully. The cutting tool material and coating, has chemically inert and excellent thermal conductivity with an aggressive rake angle with higher relief angle, improves the shearing tendency of Ti6Al4V by avoiding smearing, ultimately speculated surface quality with desired Tool life through higher Machining efficiency in milling.

Comparative Study of the Mechanical Properties and Fracture Mechanism of Ti-5111 Alloys with Three Typical Microstructures

In this work, Ti-5111 alloys with equiaxed, bimodal and lamellar microstructures were prepared by various heat treatment processes. The room-temperature tensile properties, deformation microstructure and fracture mechanism of the alloys with different microstructures were investigated. Furthermore, the mechanism by which the microstructure affects the mechanical properties of Ti-5111 alloys with three typical microstructures was confirmed. The Ti-5111 alloy with a bimodal microstructure has minimum grain size and a large number of αs/β phase boundaries, which are the primary reasons for its higher strength. Simultaneously, the excellent coordination in the deformation ability between the lamellar αs and β phases is what enables the alloy with a bimodal microstructure to have the most outstanding mechanical properties. Additionally, the presence of a grain boundary α phase and the parallel arrangement of a coarse αs phase are the main reasons for the inferior mechanical properties of the Ti-5111 alloy with a lamellar microstructure. The fracture mechanism of the alloy with an equiaxed microstructure is a mixed fracture mechanism including ductile fracture and destructive fracture. The fracture mechanisms of the Ti-5111 alloy with bimodal and lamellar microstructures are typical ductile fracture and cleavage fracture, respectively. These findings serve as a guide for the performance improvement and application of the Ti-5111 alloy.

On the Enhancement of Material Formability in Hybrid Wire Arc Additive Manufacturing

This paper is focused on improving material formability in hybrid wire-arc additive manufacturing comprising metal forming stages to produce small-to-medium batches of customized parts. The methodology involves fabricating wire arc additive manufactured AISI 316L stainless steel parts subjected to mechanical and thermal processing (MTP), followed by microhardness measurements, tensile testing with digital image correlation, as well as microstructure and microscopic observations. Results show that mechanical processing by pre-straining followed by thermal processing by annealing can reduce material hardness and strength, increase ductility, and eliminate anisotropy by recrystallizing the as-built dendritic-based columnar grain microstructure into an equiaxed grain microstructure.

Pathways to exploit the multi-spot scanning strategy in electron beam additive manufacturing for control of microstructure and defect density

The goal of this study is to investigate the impact of beam deflection pattern characteristics on microstructure and porosity formation during Powder Bed Fusion Electron Beam Melting (PBF-EB/M) processing of Inconel 718. Specifically, the complex interplay between “beam return time” and “beam jump distance” and their influence on heat accumulation, porosity, and grain formation is explored. The findings reveal that beam jump distance plays a critical role in the transition from columnar to equiaxed solidification, while beam return time is essential for achieving optimal heat accumulation and minimizing porosity. By controlling these two universal beam deflection pattern characteristics, a novel multi-spot scanning strategy was developed, enabling the formation of a fine-grained equiaxed microstructure. It is demonstrated that sufficient heat accumulation is essential for a pore-free bulk material and can be achieved by short beam return times or small beam jump distances. However, for equiaxed grain formation, a large beam jump distance, i.e., a wide distribution of melt pools, is required. Therefore, heat accumulation must be controlled by means of the beam return time if equiaxed grains are aimed for. Additionally, it is found that higher beam currents are beneficial for equiaxed grain formation, but the strongest impact on the columnar to equiaxed transition is attributed to the beam movement pattern itself. This approach offers insights into microstructure control and process reliability, regardless of the specific PBF technique employed, and enables application-specific microstructure design of Inconel 718.

Study of the irradiation hardening of a Fe9Cr ferritic model alloy by nanoindentations

This paper presents a series of Berkovich indentation results obtained on unirradiated and 7.2 MeV proton irradiated specimens of a Fe9Cr model alloy with an equiaxed ferritic microstructure. Using a energy degrader wheel made of 24 aluminum foils of different thickness, a flat damage profile of about 50 μm resulted from the irradiation, allowing to perform indentations within a volume material that is homogeneously irradiated. The indentation size effect on measured hardness was analyzed with a model based on the disloction-slip distance theory built on the concept of combined spatial frequency of all obstacles to dislocation motion. The effects on hardness of the tip-specimen contact size (or penetration depth), dislocation density and mean distance between irradiation defects were quantified and discussed. The irradiation hardening was characterized by the increase of hardness determined at large penetration depths.

Microstructure and mechanical properties of a hypereutectic Al–Si–Cu alloy manufactured by laser powder bed fusion

A novel Al–Si–Cu alloy was designed for additive manufacturing of automotive components, such as pistons and supercharger rotors, requiring a combination of elevated temperature properties and high cycle fatigue strength. The alloy was designed with an Al–Si hypereutectic chemistry to exploit the formation of primary Si nucleants to enable an equiaxed as-printed microstructure during laser powder bed fusion (LPBF). The alloy design space was assessed using a combined integrated computational materials engineering (ICME) approach with melt-spinning experiments to select a chemistry exhibiting primary Si nucleants acting as heterogeneous grain nucleation sites. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) of the LPBF as-printed samples revealed primary Si particles with a fully equiaxed grain structure and no apparent texturing as evaluated using electron backscatter diffraction (EBSD). High-resolution scanning transmission electron microscopy (STEM) revealed sub-micron Si particles and Al2Cu θ-phase precipitates which result in enhanced room and elevated temperature mechanical strength (room temperature: UTS: 449 ± 10 MPa, YS: 336 ± 12 MPa) as compared to commercial Al10SiMg (UTS: 417 ± 3 MPa, YS: 236 ± 6 MPa).

Synergic strength-ductility enhancement in bimodal titanium alloy via a heterogeneous structure induced by the 〈c + a〉 slip

In this work, a heterogeneous structure (HS) with an alternating distribution of coarse and fine α lamella is fabricated in bimodal Ti6242 alloy via insufficient diffusion of alloying elements induced by fast heating treatment. Instead of a distinct interface between the primary α phase (αp) and β transformation microstructure (βt) in the equiaxed microstructure (EM), all αp/βt interfaces are eliminated in the HS, and the large αp phases are replaced by coarse α lamella. Compared to the EM alloy, the heterostructured alloy exhibits a superior strength-ductility combination. The enhanced strength is predominantly attributed to the increased interfaces of α/β plates and hetero-deformation induced (HDI) strengthening caused by back stress. Meanwhile, good ductility is ascribed to its uniform distribution of coarse and fine α lamella, which effectively inhibits strain localization and generates an extra HDI hardening. This can be evidenced by the accumulated geometrically necessary dislocations (GNDs) induced by strain partitioning of the heterostructure. Significantly, the HDI causes extra 〈c+a〉 dislocations piling up in the coarse α lamella, which generates an extra strain hardening to further improve the ductility. Such hetero-interface coordinated deformation mechanism sheds light on a new perspective for tailoring bimodal titanium alloys with excellent mechanical properties.

Stress corrosion behavior and mechanism of Ti6321 alloy with different microstructures in stimulated deep-sea environment

The stress corrosion cracking (SCC) behaviors of Ti-6Al-3Nb-2Zr-1Mo (Ti6321, in wt%) alloy samples with equiaxed microstructure (EM), bimodal microstructure (BM) and Widmanstätten microstructure (WM) in simulated 3000 m deep sea environment were investigated using electrochemical tests, electron backscattered diffraction (EBSD), and so on. WM exhibits the best SCC resistance, which is attributed to its best self-healing ability, and is beneficial for the re-passivation of fresh metal at the crack tip. Besides, there is no obvious micro-texture region in WM with higher β phase, and α phase colonies hinder the dislocation movement, resulting in the lowest crack growth rate.

The electrochemical corrosion behavior of Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy with different initial microstructures

The corrosion behavior of Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy with different initial microstructures was investigated by conducting a series of electrochemical tests. Based on the experimental data, the effects of NaCl solution concentration and corrosion time on the electrochemical polarization curves, corrosion rates, electrochemical impedance spectroscopy (EIS), and impedance of the alloy with two initial microstructures were analyzed. The assessment of the corrosion current density (Icorr) and corrosion rate (CR) for the alloy under different corrosion conditions reveals a general pattern of initial decrease followed by increase in their values with extended corrosion time and elevated solution concentration, whereas the capacitive reactance arc exhibits an opposite trend. For alloys with initial equiaxed microstructures, the Icorr value is 0.1892 μA/cm2, and the CR value is 0.000413 mm/year; these values are lower than those of 1.298 μA/cm2 and 0.002842 mm/year for alloys with initial lamellar microstructures. Whereas the capacitive reactance arc and the impedance value are greater for the titanium alloy with initial equiaxed microstructure. Based on the adsorption kinetics principles, the effects of temperature on corrosion rate of alloys with different initial microstructures at a consistent concentration were analyzed. Compared to the alloy with initial lamellar microstructure of 3054 kJ/mol, the alloy with initial equiaxed microstructure had an activation energy of 4155 kJ/mol. As the temperature rises, the rate of corrosion tends to increase. The results suggested that the alloy with initial equiaxed microstructure presented the superior corrosion resistance than the alloy with the initial lamellar microstructure. Additionally, the corrosion morphologies after polarization of the alloy were characterized. And the results show that the surfaces of titanium alloys with initial lamellar microstructure display a comparatively greater incidence of pitting corrosion upon assessment of the corrosion morphology.

Revealing the Effects of Friction Stir Processing on the Microstructural Evolutions and Mechanical Properties of As‐Cast Interstitial FeMnCoCrN High‐Entropy Alloy

The present study aims to investigate the effect of friction stir processing (FSP) on the microstructural evolutions and mechanical properties of a nonequiatomic interstitial high‐entropy alloy (HEA). To achieve this, an as‐cast FeMnCoCrN interstitial HEA undergoes FSP to modify the as‐cast microstructure and investigate the resulting effects on mechanical properties. The grain size, sub‐boundaries, martensite fraction, and accommodated strain exhibit a gradient from the base metal (BM) to the stir zone (SZ). As a result of FSP, the average grain size in the upper SZ is significantly decreased from ≈700 μm in BM to 1.5 μm, which is around 500 times finer than that of the BM. Furthermore, the martensitic transformation in a single metastable face‐centered‐cubic phase specifically occurs in the thermomechanical‐affected and heat‐affected zones. Continuous and geometric dynamic recrystallizations triggered by FSP lead to the development of a refined equiaxed microstructure. This gradient microstructure, in turn, plays a pivotal role in achieving significantly improved mechanical properties when compared to the as‐cast microstructure. Remarkably, the yield strength doubles, the ultimate tensile strength increases from 548 to 852 MPa, and ductility increases by 16%.

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.