Strain Concentration Research Articles

Nanoscale digital image correlation at elementary fibre/matrix level in polymer–based composites

Multiscale mechanical modelling aims at predicting the failure of composites from the fibre/matrix level up to the component scale. Existing frameworks are limited by the lack of reliable experimental data and by an incomplete understanding of the submicron deformation and failure mechanisms. A novel digital image correlation (DIC) method has been developed for the characterisation of the nanoscale mechanical response in composites, based on latest advances in surface patterning. Indium has been deposited on unidirectional composites leading to a dense, homogeneous speckle with particle diameter around 15 nm. The specimens were subjected to transverse compression in a scanning electron microscope, while minimising distortion effects. Strain concentration areas, like submicron shear bands and fibre–matrix interphases, were successfully captured for two systems: a carbon fibre-reinforced thermoset and a glass fibre-reinforced thermoplastic. DIC results were compared with alternative experimental data, obtained by atomic force microscopy, and with finite element simulations based on a conventional elastoplastic model.

Comparison on crack propagation under tension at 150 °C of Mg-2Zn-1.5Mn alloy sheets with and without crack notch

Generally, edge crack of rolled magnesium alloy sheets initiates in the RD (rolling direction)-ND (normal direction) plane and then propagate in the RD-TD (transverse direction) plane. Hence, the Mg-2Zn-1.5Mn (ZM21) alloy sheets with and without crack notch were designed to carry out in-situ tensile experiments under 150 °C (the same temperature of rolling), with the aim to understand their crack propagation mechanism. The scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) techniques were utilized to reveal microstructural evolution in real time at designated displacements. The results show that the prismatic slip, basal slip, and extension twining play synergistic role in coordinating strain during the tensile process in ZM21 alloy sheet at 150 °C. In both tensile samples with and without crack notch, localized strain is mainly concentrated at relatively fine grain area and the grain boundaries or triple junctions of the grains with large basal Schmid factor (SF) difference, which eventually leads to severe surface roughening and subsequent crack initiation. Compared with the sample without crack notch, the pre-cracked sample exhibits severer deformation at the crack tip due to strain concentration. Strain gradient distribution is observed at the crack tip region in the pre-cracked sample. The crack propagation path of the sample with pre-crack is identified and the underlying mechanism is also discussed.

Antimycobacterial Activity of Hedeoma drummondii against Mycobacterium tuberculosis and Non-Tuberculous Mycobacteria.

Tuberculosis (TB) remains a major health problem worldwide, and the emergence of multi-resistant strains to first-line drugs has become the biggest obstacle to its treatment. On the other hand, the incidence of non-tuberculous mycobacteria (NTM) in humans has increased remarkably in recent years. The search for new and better treatments against mycobacterial infections is a constant at the global level. Hence, in this study, we propose to investigate the antimycobacterial effect of the extracts and major compounds of Hedeoma drummondii against clinical isolates of Mycobacterium tuberculosis and non-tuberculous mycobacteria: M. abscessus, M. fortuitum, M. intracellulare, and M. gordonae. To determine the antimycobacterial activity, a microdilution assay was used to establish the minimum inhibitory concentration (MIC) of the different strains of Mycobacterium. The methanolic extract presented the best activity against M. tuberculosis, inhibiting ten of the twelve strains analyzed at a concentration < 2500 µg/mL; meanwhile, the hexanic extract presented the best activity against non-tuberculous mycobacteria (NTM) by inhibiting eight of the ten strains studied at ≤625 µg/mL. Moreover, there is a strong positive correlation between the antimycobacterial activity of pulegone and the hexanic extract against non-tuberculous strains, so this compound could serve as a predictability marker against these types of microorganisms.

Effects of temperatures on microstructure evolution and deformation behavior of Fe–32Ni by in-situ EBSD

Fe–32Ni alloy has attracted the attention of researchers owing to its excellent thermal expansion properties and mechanical properties. In this study, the macroscopic mechanical properties, surface morphology, crystal orientation, evolution of grain boundary and kernel average misorientation (KAM) and deformation mechanism of Fe–32Ni alloy were systematically investigated by in-situ loading equipment from 25 °C to 800 °C combined with electron backscatter diffraction (EBSD). The results showed that the grains with (111) and (101) orientations formed a special ring texture in {100} and {110} poles of the polar diagram after grain deformation and rotation. The rotational ability of the grains with (111) and (101) orientations were significantly promoted as the temperature increased. The number and proportion of low-angle grain boundaries (LAGBs) increased with increasing strain and temperature. By analyzing the microstructure evolution during in-situ EBSD testing, it was found that the rotation of the crystals significantly improved the deformability of the material. The effect of selective passage for dislocations by LAGBs both enhanced the plasticity and caused hardening of the material. Dislocations tended to accumulate at grain boundaries causing strain concentration. Cracks sprouted at grain boundaries and expand along the grain boundaries. This study can provide profound insights on the deformation mechanism of Fe–32Ni alloy for the possible design and process optimization.

Intragranular thermal fatigue of Cu thin films: Near-grain boundary hardening, strain localization and voiding

In order to obtain a fundamental understanding of the phenomena accompanying thermomechanical fatigue of Cu metallization used in power electronics, as well as the resulting deterioration of electric properties, there is a need to assess intragranular microstructure and strain evolution within individual Cu grains and near grain boundaries. Here, synchrotron dark field X-ray microscopy (DFXM) is used to characterize as-deposited and 5 × 104 times thermally-cycled 20 µm thick Cu films. The cycling was performed using a dedicated test chip in the range of 100–400 °C applying a heating rate of 106 K/s. The thermomechanical treatment results in severe shear deformation of Cu grains, film surface roughening, gradual grain microstructural refinement, the emergence of microscopic voids preferably at high angle grain boundaries (HAGBs) and finally in the voids' percolation, as revealed by in-situ and ex-situ scanning electron microscopy. DFXM provides experimental evidence that mosaicity of Cu grains, residual tensile and compressive elastic strain concentrations and full width at half maximum of Cu 111 reflections increase simultaneously in the vicinity of the HAGBs. The latter is interpreted as resulting from vacancy condensation in front of the HAGBs, after dislocations have moved across cycled grains and partly annihilated. Moreover, the observed HAGB decohesion and gradual void formation are correlated with the supposed hardening of regions near HAGBs, which thus lose their ductility during cyclic elasto-plastic deformation. The results are complemented with the ex-situ X-ray nanotomography data, which document the voids' percolation across the film's thickness with a “crack” width of up to ∼2 µm. In general, the study identifies the inhomogeneous intragranular microstructural refinement and a gradual condensation of structural defects near HAGBs as driving forces for void formation in thick Cu metallizations during fast thermo-mechanical fatigue.

Characterising Solder Materials from Random Vibration Response of Their Interconnects in BGA Packaging

Solder interconnection in electronic packaging is the weakest link, thus driving the reliability of electronic modules and systems. Improving interconnection integrity in safety-critical applications is vital in enhancing application reliability. This investigation qualifies the random vibration response of five essential solder compositions in ball grid array (BGA) solder joints used in safety-critical applications. The solder compositions are eutectic Sn63Pb37 and SnAgCu (SAC) 305, 387, 396, and 405. Computer-aided engineering (CAE) employing ANSYS finite element analysis and SolidWorks software is implemented in this investigation. The solder Sn63Pb37 deformed least at 0.43 µm, followed by SAC396 at 0.58 µm, while SAC405 deformed highest at 0.88 µm. Further analysis demonstrates that the possession of a higher elastic modulus and mass density culminates in lower solder joint deformation. Stress is concentrated at the periphery of the solder joints in contact with a printed circuit board (PCB). The SAC396 solder accumulates the lowest stress of 14.1 MPa, followed by SAC405 at 17.9 MPa, while eutectic Sn63Pb37 accrues the highest at 34.6 MPa. Similarly, strain concentration is found at the interface between the solder joint and copper pad on a PCB. SAC405 acquires the lowest elastic strain magnitude of 0.0011 mm/mm, while SAC305 records the highest strain of 0.002 mm/mm. These results demonstrate that SAC405 solder has maximum and SAC387 solder has minimum fatigue lives.

Experimental study on the dynamic splitting tensile properties of polyvinyl-alcohol-fiber-reinforced cementitious composites

In this study, the dynamic splitting performance and energy absorption capacity of polyvinyl- alcohol-fiber-reinforced engineered cementitious composites were studied using a split Hopkinson pressure bar system. By using a high-speed camera, changes in the surface strain fields and crack expansion patterns of specimens under different striking pressures were observed and validated, and experimental results for four types of fiber-reinforced concrete and one type of plain concrete without PVA fibers were obtained. The strain-rate effect on the dynamic tensile strength of fiber-reinforced concrete and plain concrete was confirmed. Digital image correlation measurement results indicate that microcracks were present near the radial primary cracks in the fibrous concrete, where strain concentration zones were formed. Additionally, PVA fibers can effectively reduce the rate of decline following the peak in the localization factor, and the PVA fibers begin to play a bridging role following the generation of microcracks, which slows the damage development of specimens, allowing them to absorb more impact energy.

Study of Mechanical Behavior and Deformation Field Characteristics of Sandstone under Cyclic Loading

The sandstone yield strength and tensile strength were increased under cyclic loading paths by using the Brazilian splitting method. The experiment shows that (1) the sandstone specimens exhibit multiple penetrating crack damage by cyclic loading, while the tensile strength slightly increases; (2) the sandstone horizontal strain (Exx) concentration area decreases, and the shear strain (Exy) concentration area increases under cyclic loading, and the damage form changes from completely brittle tensile damage to ductile mixed tensile-shear damage; (3) the mechanism of the increase in tensile strength of the specimen under cyclic loading was explained by digital image correlation (DIC) technique. The results indicate that a time lag occurs in the horizontal strain concentration zone, and the area of the penetration zone decreases from the cyclic loading effect, while the reduced stress concentration leads to increased tensile strength of the specimens.

Suction Cup Quality Predication by Digital Image Correlation

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Vacuum suction cups are used as transforming handles in stamping lines, which are essential in developing automation and mechanization. However, the vacuum suction cup will crack due to fatigue or long-term operation or installation angle, which directly affects production productivity and safety. The better design will help increase the cups' service life. If the location of stress concentration can be predicted, this can prevent the occurrence of cracks in advance and effectively increase the service life. However, the traditional strain measurement technology cannot meet the requirements of tracking large-field stains and precise point tracking simultaneously in the same area, especially for stacking or narrow parts of the suction cups. The application must allow multiple measurements of hidden component strain information in different fields of view, which would add cost. In this study, a unique multi-camera three-dimensional digital image correlation (3D-DIC) system was designed and applied to measure the strain concentration of the suction cups while the cups were running the pulling progress. In this technique, a multiplexed quad-cameras DIC system which contains two sets of 3D-DIC system (4 cameras) with different field of view or different measurement directions enables simultaneous measurement of full-filed and hidden parts under the same calibration progress. The first two cameras built a sub-group of the 3D-DIC system, which was used to measure the local strain of the narrow or stacked prats. The other system was used to acquire the strain fields of the entire suction cup. In addition to the experimental test, the fatigue test to see the cracks appeared location. The results of DIC were compared to the fatigue data, and the DIC experimental data validated the crack location. This project aims to help designers and operators thoroughly understand the performance of vacuum cups by investigating the strain concentration and crack location.&lt;/div&gt;&lt;/div&gt;

Effect of medium-speed forming on formability of tailor welded blanks

Despite the widespread use of tailor welded blanks (TWB) in manufacturing auto-body panels and considering that different forming processes are performed at various speeds, it is necessary to examine the forming speed consequences. So, this study aims to investigate the forming speed effect on the formability of TWB and its constituent sheets. TWB consisting of St14 steel sheets of different thicknesses were welded using a fiber laser. Uniaxial tensile tests were conducted at various strain rates, and formability experiments were carried out at the quasi-static and medium-speed forming to construct forming limit curves (FLC). Tensile test results showed that some strain-hardening indicators decreased by strain rate increasing. The flow stress of base metals at different strain rates was successfully predicted by the constitutive model considering variable parameters. At medium-speed forming of base metals, the peak of major strain and fracture moved to the dome center. But, the strain concentration of most TWB samples at two forming speeds occurred in the thin sheet near the dome center. Also, the limiting dome height (LDH) at medium-speed forming decreased. Medium-speed FLC of base metals shifted downward and to the more positive minor strain compared to quasi-static FLC. Medium-speed FLC of TWB was lower than quasi-static FLC, especially on the tension-compression side. The reduction of medium-speed formability was attributed to the strain-hardening lowering, friction reduction, and inertial effects due to increased forming speed.

Macro and micro investigation of fracture behavior and crack evolution considering inherent microcrack in prefabricated flawed granite

The existence of inherent microcracks in granite makes accurately describing crack propagation and fracture behaviors challenging, which is crucial in engineering applications. We found that the crack propagation was competitively affected by the geometry of the flaw and inherent microcracks. During the process of semi-circular bending, the width of the fracture process zone was influenced by the inherent microcracks, whereas the length was not. The existence of inherent microcracks broadened the fracture process zone and increased its influence scope. The fracture process zone and isolated strain concentration caused by inherent microcracks coalesced to form a continuous fracture path. Additionally, the fracture toughness with size dependence was discussed using the data obtained from simulation.

Meso-macro constitutive model for frozen salinized sandy soil

In the permafrost areas, the frozen salinized sandy soil is a unique geotechnical component whose mechanical properties will influence the stability of engineering. Thus, formulating a constitutive model for frozen salinized sandy soil has significance scientifically for the design of engineering in cold regions. Combining the theoretical framework of breakage mechanicals for materials, micromechanical analysis method, and homogenization method, a meso-macro constitutive model for frozen salinized sandy soil is put forward in this research. In the proposed model, considering the structure characteristics, the frozen salinized sandy soil is abstracted as a type of inhomogeneous binary materials, the bonded elements composed of the unbroken ice crystals, salt crystals, and soil particles, behaving elastic-brittle mechanical properties, and the frictional elements composed of the broken ice crystals, salt crystals, and soil particles, with elastic-plastic mechanical properties. Due to the disparity in the mechanical characteristics of the constituent materials, the impact of salt concentration on the mechanical parameters of the bonded elements is also taken into consideration. Moreover, the nonuniform distribution of stress and strain with the representative volume element is described by introducing the breakage ratio with the derivation of the strain concentration tensor. The comparison with the tested results demonstrates that the proposed mese-mace constitutive model could simulate the stress-strain and volume law of frozen salinized sandy soil under different confining pressures, which has satisfactory adaptability to reflect the physical and mechanical properties of frozen salinized sandy soil.

Slip Band Evolution Behavior near Circular Hole on Single Crystal Superalloy: Experiment and Simulation

Circular holes on single crystal (SX) superalloys are widely utilized as film cooling structures on SX turbine blades, while their failure is a persistent issue. This study presents in-situ tests using digital image correlation (DIC) to reveal the slip band (SB) evolution behavior near the circular hole on SX superalloy, and proposes a mechanism-based model to capture the SB-associated evolutions of stress, strain, and damage fields. In the experiment part, high-temperature in-situ tensile tests are carried out under scanning electron microscope on plate-like SX specimens with circular hole, which can achieve the in-situ measurement and observation for the SB-induced strain concentration and microcrack nucleation. Experimental results reveal the effects of secondary orientation and temperature on stress-strain curve, SB evolution and SB direction. Besides, the microstructure observation shows that the γ´ phase shear is the primary cause of strain concentration inside SB. In the simulation part, a physics-based SB evolution model is proposed under the framework of crystal plasticity. For the regions inside and outside SB, different critical resolved shear stresses are utilized as the plasticity criteria, and different slip resistances are used as internal state variables in the flow rule to simulate the SB-induced strain concentration. A damage evolution rule is developed based on the plastic work density in slip systems to simulate the microcrack nucleation near the hole edge. Finally, the proposed model is validated through the experiments. The model can effectively simulate the SB initiation/evolution, SB direction, SB-induced strain concentration, and the microcrack nucleation near circular hole on SX superalloy.

Nematode predatory ability of the fungus Duddingtonia flagrans affected by in vitro sequential exposure to ovine gastrointestinal tract

Duddingtonia flagrans is a nematophagous fungus employed as a biocontrol agent of gastrointestinal nematodes in ruminants. After oral ingestion and passage through the digestive tract of animals, this microorganism captures the nematodes in the feces. The drastic conditions of ruminant digestive tract could affect fungi chlamydospores and therefore biocontrol activity. The aim of this study was to evaluate in vitro the effect of four ruminant digestive segments on the concentration and nematode predatory ability of a Colombian native strain of D. flagrans. The sequential four-step methodology proposed evaluated conditions of the oral cavity, rumen, abomasum, and small intestine such as pH (2, 6, 8), enzymes (pepsin, pancreatin), temperature (39 °C), and anaerobiosis comparing short (7 h) and long (51 h) exposure times. The results showed that the nematode predatory ability of the fungi is affected by sequential exposure to gastrointestinal segments and this effect depends on the exposure time to those conditions. After short exposure (7 h) through the four ruminant digestive segments, the fungi had a nematode predatory ability of 62%, in contrast, after long exposure (51 h) the nematode predatory ability was lost (0%). Moreover, the number of broken chlamydospores was higher in the long-exposure assay.

Response Surface Analysis of Process Parameters for Thermocompression Ultrasonic Flip Bonding of Chips

Thermocompression ultrasonic flip bonding has been widely used in semiconductor packaging. In order to better understand the mechanism of bonding interface formation of thermocompression ultrasonic flip bonding. A three-dimensional (3D) dynamics finite element model of the chip, gold bumps, and substrate was developed, which considers the softening effect of gold bumps during the bonding process. The effects of pressure application position, pressure magnitude, temperature, and ultrasonic power on the stress and plastic strain in the chip, gold bumps, and substrate were analyzed. The results indicated that the maximum stress and plastic strain occurred at gold bumps and the edge of under-bump metallization (UBM) layers for the global model, while the maximum stress at a single bump appeared in the central region. The pressure application position had a minor effect on reducing stress concentration, but had a significant effect on reducing plastic strain concentration. The pressure under various amplitudes had a major effect on the stress, while temperature had a minor effect. The results may provide some references for thermocompression ultrasonic flip bonding of chips.

On the strengthening and slip activity of Mg-3Al-1Zn alloy with pre-induced {101¯2} twins

{101¯2} twins were introduced into the magnesium (Mg) plate AZ31 via pre-rolling along its transverse direction. The plates, both with and without the pre-induced {101¯2} twins, were subjected to uniaxial tension along different directions. Using crystal plasticity modeling, we found that the strengthening effect of the pre-induced {101¯2} twins on the macroscopic flow stress primarily arised from the increased slip resistance caused by the boundaries, rather than the orientation hardening due to the twinning reorientation (although the latter did make its contribution in some specific loading directions). Besides, the pre-existing {101¯2} twins were found, by both experiments and simulation, to promote the activity of prismatic 〈a〉 and pyramidal 〈c + a〉 in the parent matrix of the material. Further analysis showed that the enhanced non-basal slip activity is related to the {101¯2} twin boundaries' low micro Hall-Petch slope ratios of non-basal slips to basal slip. With the critical resolved shear stress (CRSS) obtained from crystal plasticity modeling and the orientation data from EBSD, a probability-based slip transfer model was proposed. The model predicts higher slip transfer probabilities and thus lower strain concentration tendencies at {101¯2} twin boundaries than that at grain boundaries, which agrees with the experimental observation that the strain localization was primarily associated with the latter. The present findings are helpful scientifically, in deepening our understanding of how the pre-induced {101¯2} twins affect the strength and slip activity of Mg alloys, and technologically, in guiding the design of the pre-strain protocol of Mg alloys.

Magnetic flux leakage detection based on a sensitivity-enhanced fiber Bragg grating magnetic field sensor.

We propose a sensitivity-enhanced fiber Bragg grating (FBG) magnetic field sensor for magnetic flux leakage (MFL) detection. The testing system consists of the FBG, suspended strain concentration structure, and two ceramic tubes bonded on a Terfenol-D base. We show the relation between the MFL and the width and depth of the crack, the lift-off of the sensor away from the surface of the workpiece, and the angle between the orientation of the sensor and the magnetization direction. The experimental results are very consistent with those obtained from finite element analysis simulations. The sensitivity of the sensor is increased to 81.11pm/mT for increasing magnetic fields and 91.55pm/mT for decreasing magnetic fields. The MFL test demonstrates that the sensor can identify a crack with a width of 0.5mm and depth of 2mm in an 8mm thick workpiece. To the best of our knowledge, the magnetic field sensor proposed in this work has the highest sensitivity compared with the same types of sensors. Moreover, the application of an FBG-Terfenol-D based magnetic field sensor in the MFL test shows good performance. Compared with traditional electrical MFL testing technologies, the sensitivity-enhanced optical fiber magnetic field sensor has a higher resolution and longer survival time in harsh environments.

Kinetic modeling of xylonic acid production by Gluconobacter oxydans: effects of hydrodynamic conditions

In this study, the synthesis of xylonic acid from xylose by Gluconobacter oxydans NL71 has been investigated. According to the relationship between oxygen transfer rate and oxygen uptake rate, three different kinetic models of product formation were established and the nonlinear fitting was carried out. The results showed that G. oxydans has critical dissolved oxygen under different strain concentrations, and the relationship between respiration intensity and dissolved oxygen conformed to the Monod equation [Formula: see text]. The maximum reaction rate per unit cell mass and the theoretical maximum specific productivity of G. oxydans obtained by the kinetic model are 0.042mol/L/h and 6.97g/gx/h, respectively. These results will assist in determining the best balance between the airflow rate and cell concentration in the reaction and improve the production efficiency of xylonic acid.

Evaluation and Comparison of Stress in Divergent and Convergent Collar Designs of Implants With Different Bone Densities: A Finite Element Study.

The failure and the success rate of an implant depends on biomechanical factors, esthetics and painless sterile implant surgery conditions, out of which stresses applied to the bone and its surrounding, bone-implant interface, material characteristics of the implant used and the strength of the bone and its surrounding are the important factors. This study aimed to evaluate the stress distribution of divergent collar design (DCD)and convergent collar design (CCD) implants placing them in four different densities of the bone (D1, D2, D3 and D4).The evaluation of the stress distribution of DCDand CCD was performed using the 3D finite element method (FEM), by placing them in four different bone densities.In addition to this, a comparison of the effect of DCD and CCD in terms of stressdistribution in the bone was also done. The softwareused to process the geometric characteristics of the missing first molar in the mandibular section were Ansys, version 19.2, CATIA, version 5, and Solidworks (Dassault Systèmes). Using these software, three models were designed and successfully restored using an all-ceramic crown implant. The first model was a geometric modelof the first molar mandibular bone section, the second model was a cylindrical implant (4x10mm) with a DCD and CCD, and the third model had titanium alloy (Ti-6Al-4V) properties incorporated into the implant. The D1 bone model showed the lowest stress concentration compared to D2, D3, D4. The DCD showed the lower stress and strain concentrations as compared to the CCD in the contiguous crestal bone in all the densities of the bone in both vertical and lateral or oblique loadings. The DCD with the D1 bone showed the least stress concentration around the crestal bone region. The results of this study also showed that the maximum von Mises stress was observed in the crestal region or the neck of the implant for both the convergent and divergent collar implant designs in all the four densities of the bone. Before a patient trial of a new implant design or a new implant material, finite element analysis (FEA) gives us a clear picture of what will be the patient bone response when an implant will be placed and loaded. FEA also gives us an opportunity to test a new implant material without putting a patient at risk. In this study, four different types of bone were incorporated with two different implant collar designs. Each implant assembly was subjected to vertical as well as oblique forces. The response of each bone type for the titanium alloy implant was recorded. A color-coded response for the magnitude and the location of the maximum stress received by the bone was observed.Maximum stresses were seen in the crestal region. As this is a computer-based model, dynamic loading was not possible. This study provided us with the possible outcome in patients under a static load. Further studies can be conducted invivo to record dynamic loading responses as well as long-time loading responses.

Effect of Scanning Strategies on the Microstructure and Mechanical Properties of Ti-22Al-25Nb Alloy Fabricated through Selective Laser Melting

In this study, Ti-22Al-25Nb intermetallic compound alloys are fabricated through selective laser melting (SLM) at four scanning speeds (600, 700, 800, and 900 mm/s). The microstructure and mechanical properties of the selective laser melting fabricated alloys are systematically evaluated. The results indicate that scanning speed significantly affects microstructure characteristics (e.g., relative density, grain size, texture density, and the precipitation of secondary phases). The variation laws of the relative density, grain size, and texture density are likewise affected by scanning speed. The relative density, grain size, and texture density increase and then decrease with the increase in scanning speed. The alloy fabricated with the lowest scanning speed (600 mm/s) exhibits the maximum relative density, grain size, and texture density. By contrast, the alloy with the highest scanning speed (900 mm/s) exhibits the minimum relative density, grain size, and texture density. Furthermore, the precipitations of the O phase and Ti3Al phase are primarily distributed in regions with a high strain concentration near the pool boundary. The alloy fabricated with a 600 mm/s scanning speed simultaneously achieves the highest strength and elongation, which is closely correlated with the uniform distribution of secondary phases.