Magnesium alloys face the inherent challenge of the strength-ductility trade-off due to their limited room-temperature ductility and pronounced processing texture. To address this issue, this study employs isothermal multidirectional forging to synergistically regulate the basal texture and long-period stacking ordered phase in a Mg-7Y-2.5Zn-0.5Zr-0.1V alloy by introducing a dynamic multi-axial strain field. The microstructures, deformation mechanisms and room-temperature mechanical properties of the alloys processed by IMDF at different temperatures (370°C, 420°C and 470°C) were systematically investigated. Results demonstrate that IMDF can significantly weaken the basal texture, optimize the morphology and distribution of the LPSO phase, and refine the grains simultaneously. The IMDF–420 alloy achieves an optimal balance of strength and ductility, with superior room-temperature tensile properties (YS: 335.6 MPa, EL: 27.2%). Its strengthening mechanisms include Hall-Petch strengthening from grain refinement, accumulation of GNDs and back-stress hardening induced by misorientation of grains, as well as the synergistic strengthening and toughening effects of multi-scale second phases (LPSO phase and short-range ordered (SRO) structure). In contrast, the excellent ductility originates from the combined activation of multi-slip systems induced by weak texture, grain refinement and dispersed LPSO phases. Specifically, the extensive activation of pyramidal ⟨c+a⟩ slip lays the foundation for macroscopic high ductility, while the twinning-slip transition, kinking and breaking of the LPSO phase, and intergranular slip transfer collectively form an efficient strain release system, which avoids severe strain localization and premature damage. This work provides important theoretical basis and process guidance for the design of high-performance magnesium alloys via multi-directional deformation processes.

To investigate the oxidation behavior of TC4 alloy at 700 °C in air and the possible mechanism for the oxidation-rate transition under this condition, isothermal oxidation experiments and first-principles calculations were combined. Oxidation kinetics showed that the alloy’s mass gain increased with time, whereas the apparent oxidation rate gradually decreased, suggesting an increase in the transport resistance of the developing oxide scale. Characterization revealed that TiO2 with the P42/mnm structure was the dominant crystalline oxide, while a minor amount of Al2O3 with the R3̅c structure was detected. SEM/EDS and semi-quantitative XRD results indicated progressive oxide-scale thickening and later-stage Al enrichment within the oxide-scale region. First-principles calculations indicated that Al incorporation altered the local electronic structure and bonding characteristics of α-Ti surfaces, yet the initial oxidation was dominated by Ti forming TiO2, followed by surface Al enrichment and the formation of more stable Al2O3. Further analysis of the electronic structure and charge distribution showed that the Al–O bond is more ionic and that Al2O3 is denser and more structurally stable, suggesting stronger intrinsic protective characteristics than TiO2. Combining experimental observations and theoretical calculations, a possible oxidation-rate transition mechanism of TC4 alloy at 700 °C is proposed: “Ti-preferential oxidation—Al redistribution—development of Al-enriched or Al2O3-containing oxide regions”, explaining the transition from rapid initial mass gain to inhibited subsequent oxidation.

Titanium alloy large-scale rib-web components, known for their lightweight and high-strength properties, have the potential to substantially lighten the load-bearing components of aircraft. Isothermal Local Loading (ILL) has been recognized as an advanced technique for the integrated and less-loading forming of these components. However, material transfer in the transitional region during ILL often leads to folding defect near the die-partition line. To this end, the position of the neutral layer during ILL is calculated via the slab method, which is modified to align with the material flow in the transitional region, taking into account the multi-stage stress states under diverse boundary conditions. By utilizing this calculation model, the material transfer rate and rib-groove filling height can be ascertained. The material transfer rate serves as a criterion for predicting folding defect, and thereby an optimal billet is obtained and implemented in the ILL process. The results demonstrate that the material transfer rate is significantly decreased compared to the non-optimized billet, resulting in a non-folding component of transitional region.

Hot backward extrusion is widely used for magnesium alloy cups. Limited ductility and non-uniform flow make the corner prone to cracking. An EZ30 Mg cup was studied by EBSD and DEFORM-3D simulations. The Oyane ductile fracture criterion was used to evaluate damage evolution. Simulations and experiments show a consistent failure sequence. Damage localizes first on the outer corner side. The crack then propagates toward the inner filet between the cup bottom and wall. Punch tilt raises the maximum damage by 13.3

Titanium/carbon-fiber composite hybrid joints require robust metal/polymer interfaces to exploit the complementary properties of titanium alloys and fiber-reinforced polymers. In this study, TA15 composite coatings with dry-GNP/TA15-powder mass ratios of 0.00-1.00 wt% were deposited by doctor blade and vacuum-sintered at 1050 °C before co-curing with carbon-fiber/epoxy prepreg. Coating morphology, phase and chemical-state evolution, apparent wettability, single-lap shear strength (SLSS), and fracture morphology were evaluated. The 0.25 wt% formulation produced the highest measured group-mean SLSS (30.9 MPa), compared with 10.2 MPa for the untreated TA15 control and 16.5 MPa for the GNP-free porous coating. SEM revealed an interconnected sintered-particle network that enables epoxy penetration and mechanical interlocking. Raman spectroscopy, XPS, XRD, and EDS were collectively consistent with carbon redistribution and Ti-C-rich regions at the titanium side of the interphase. Fractography showed a pronounced shift from predominantly adhesive failure for the untreated TA15 control to resin-rich/cohesive failure for the 0.25 wt% formulation, with Ti-side residual-resin coverage increasing from less than 5% to approximately 99%. The results support hierarchical strengthening through porous mechanical interlocking, titanium-side chemical modification, and improved load transfer into the polymer-rich region.

Twin roll cast (TRC) AZ31 magnesium alloy sheets combine high processing efficiency with microstructural homogeneity, offering significant potential for advanced forming processes and high-end structural applications. However, the evolution of texture-induced anisotropy during hot rolling and the underlying mechanisms enabling simultaneous high strength and ductility remain insufficiently understood. In this study, the microstructural evolution and anisotropic mechanical response of TRC AZ31 sheets during hot rolling are systematically investigated through integrated experiments and mechanism-based modeling. Detailed characterization reveals that dynamic recrystallization (DRX)-induced grain refinement and the strengthening of the basal <0002>//TD texture dominate the mechanical response and anisotropy of the rolled sheets. Hot rolling substantially increases both yield strength and ultimate tensile strength, whereas the intensified basal texture limits ductility, leading to a characteristic strength-ductility trade-off with strong directional dependence. To elucidate the interaction between slip and twinning, a relaxed-constraint Sachs (RC-Sachs) constitutive model is developed, incorporating texture statistics, slip-twin activation, and grain-size effects. The model accurately reproduces orientation-dependent stress-strain responses across distinct texture states, with a mean error below 5%, and quantitatively captures the texture-controlled transition of operative deformation mechanisms. The analysis further identifies that moderate weakening of the basal texture, combined with enhanced grain refinement, provides an effective pathway for achieving concurrent high strength and ductility. This work establishes a mechanistic foundation and a predictive modeling framework for the integrated optimization and performance-oriented design of magnesium alloy sheets.

A slight difference in extrusion temperatures (450 degrees C and 500 degrees C) brought about significant variation in the mechanical properties of Mg-9.5Gd-4Y-2Zn-0.5Zr (wt%) alloy during the ultra-large ratio (100:1) hot extrusion. Such variation was investigated through the comparison of microstructure evolution as well as its effect on the mechanical properties. Results showed that the sample extruded at 450 degrees C (T450 sample) possessed a finer average grain size of 2.3 mu m due to dynamic recrystallization (DRX), while increasing the extrusion temperature to 500 degrees C caused the obvious migration of grain boundaries in the extrusion sample (T500 sample), coarsening the grain size to 7.9 mu m. Importantly, such DRXed grains in the T450 sample showed random orientation, which weakened the deformation texture and consequently led to the formation of a weak [10-10] fiber texture finally. In contrast, the T500 sample exhibited preferred nucleation and growth of DRXed grains, eventually developing the strong [0001]//ED recrystallization texture. The finer DRXed grains and retained deformation microstructure in the T450 sample produced significantly higher yield strength (YS) and ultimate tensile strength (UTS) of 402 MPa and 477 MPa compared to the T500 sample (YS: 343 MPa; UTS: 433 MPa). Actually, the T450 sample should possess much higher strength originally if its weak texture did not weaken the grain boundary strengthening and dislocation strengthening effects. Additionally, the LPSO phases in the T450 sample exhibit a greater width than the T500 sample, producing smooth tearing ridges, sparse dimples, and a lower fracture elongation of 13.4 % (T500 sample: 16 %).

This study introduces Ti6Al4V2Fe, a novel dual-phase titanium alloy, manufactured via Cold Metal Transfer Directed Energy Deposition (CMT-DED) for aerospace applications. This alloy meets stringent performance demands and enables efficient additive manufacturing of large-scale components. We investigated its microstructural evolution and mechanical properties under static and dynamic conditions. Room temperature tensile tests and dynamic impact assessments (1500/s to 3000/s) revealed a refined microstructure with short columnar and fine equiaxed prior-beta grains, influenced by undercooling and thermal gradients. The addition of Fe enhanced beta phase nucleation, resulting in a basket-weave alpha + beta structure. Dynamic tests highlighted increasing strength with strain rate, with horizontal samples displaying superior strength. A constitutive model confirmed the experimental stress-strain profiles. At 2500/s, adiabatic shear bands indicated heightened sensitivity in horizontal samples, while vertical samples absorbed more energy, linked to dynamic recrystallization. The Ti6Al4V2Fe alloy, fabricated by CMT-DED, demonstrates remarkable strength, enhanced toughness, and reduced anisotropy, marking it as a prime candidate for aerospace applications.

To further investigate the corrosion resistance of titanium matrix composites, this paper successfully established a columnar network distribution of 5 vol.

In order to further enhance the high-temperature wear resistance of titanium alloys, a columnar network distribution of TiB whiskers was introduced into TA15 titanium alloy to form high wear-resistant TiBw/TA15 composites. High-temperature wear experiments were conducted on composites with varying TiBw volume fractions to investigate the impact of the reinforcing phase volume fraction on the high-temperature wear performance of the composites, as well as the microstructural evolution behavior near the wear surface. Research results indicated that the high-temperature wear surface displayed phenomena such as plowing grooves, micro-cracks, and wear debris. These observations suggested that the high-temperature wear mechanism of the composites involved a combination of abrasive wear, adhesive wear, and fatigue wear. The high-temperature wear resistance of TiBw/TA15 composites increased with the content of the reinforcing phase. Specifically, when the TiBw content was 7.5 vol%, the wear rate of the composites was 8.9 x 10_6 mm3/(N center dot m), representing a reduction of 78.4 % compared to that of 2.5 vol% composites. This improvement was attributed to the high concentration of TiB whiskers, which effectively enhanced the deformation resistance and hardness of the composites while refining the matrix grain size. These findings could provide a theoretical foundation for the application of titanium-based composites in high-temperature wear environments.

This work focuses on the microstructure evolution and mechanical properties of the Mg-9.5Gd-4Y-2Zn-0.5Zr alloy wire during the multi-pass drawing at 300 degrees C. Results showed that the deformed grains were elongated and concurrently some clusters of ultra-fine dynamically recrystallized (DRXed) grains appeared owing to the combined effects of the low temperature and cumulative strain. These ultra-fine DRXed grain boundaries combined with some subgrain boundaries in deformed grains provided abundant precipitation sites, promoting dynamic precipitation of Mg5RE phases under sufficient cumulative strain. Such severe strain also made the LPSO phases fracture along DD (drawing direction) and contract along TD (transverse direction). In addition, the activation of basal slip rotated the basal plane to the DD, and under the extra axisymmetric strain effect, the basal plane spread along the TD. Subsequently, the prismatic slips were forced to be activated and rotated the < 10-10 > crystal direction to DD, eventually developing one < 10-10 > //DD texture. This variation in texture enhanced the grain boundary hardening effect. According to the quantitative analysis of the hardening mechanism, the combined effect of the grain boundary hardening and dynamically precipitated Mg5RE phases mainly increased the Vickers hardness with the strain cumulating, which resulted in the hardness increasing to 132HV from 113HV when the wire diameter reduced to 2.5 mm during the multi-pass drawing.

Balancing strength and ductility in magnesium alloys is challenging because texture and grain size jointly govern slip activity and strain accommodation. This study produced diversified microstructures in extruded Mg-9Gd-5Y0.5Zr by tailoring extrusion temperature and extrusion ratio to control dynamic recrystallization and preferential grain growth. Electron backscatter diffraction was used to quantify texture; a basal-equivalent orientation factor Mwas derived within the Taylor assumption; geometrically necessary dislocation densities were evaluated using Nye's tensor. A modified Hall-Petch model (GM-HP, where G denotes the GND-based term and M denotes the orientation factor) integrated texture, grain-boundary, and dislocation contributions to estimate yield strength. The processing window generated deformation microstructures with varied dispersion of the < 10-10 > // extrusion direction (ED) component and DRXed microstructures with varied dispersion of the <0001 > //ED component, yield strengths (YS) of 157.6-256.9 MPa and uniform elongations (UEL) of 14.2-24.4 %. Dispersion of the < 10-10 > texture promotes basal slip, enhancing UEL to 24.4%, whereas development of a <0001 > texture increases the fractional contribution of pyramidal slip and is associated with higher YS about 260 MPa. The results provide a quantitative, mechanism-based foundation for microstructure-guided strength-ductility design in wrought RE-containing magnesium alloys.

To further investigate the corrosion resistance of titanium matrix composites, this paper successfully established a columnar network distribution of 5 vol.% TiBw/TA15 composites using a low-energy ball milling and hot extrusion process. The electrochemical corrosion behavior of composites was studied and analyzed before and after the hot extrusion process in a simulated marine environment (3.5 wt.% NaCl solution). The result indicated that the corrosion resistance of the 5 vol.% TiBw/TA15 composites was enhanced after the hot extrusion process. This was because, during the hot extrusion process of 5 vol.% TiBw/TA15 composites, dynamic recrystallization occurred, leading to a more uniform distribution of alloying elements in composites after hot extrusion. This process mitigated the galvanic effect caused by the segregation of alloying elements, reduced the corrosion rate of the composite materials, and consequently enhanced their corrosion resistance.

Owing to the high-temperature preparation processing of GNPs (Graphene nanosheets)/TA15 matrix composites, severe interfacial reactions arose between GNPs and Ti matrix. To overcome above problem, the boron (B) element was innovatively introduced to control the interface reaction of GNPs/TA15 composites by a technological process of "3D network (GNPs/B/TA15) structure + spark plasma sintering (SPS) + canned hot extrusion". The effects of different extrusion temperatures (900-1050 degrees C) on the microstructure and mechanical properties were deeply investigated. The results revealed that B atoms preferentially diffused into the Ti matrix rather than into GNPs during SPS. The directional diffusion of B atoms into the Ti matrix was driven by alterations in the chemical potential of B on the surface of TA15 powders, induced by discharge plasma and temperature gradient. During hot extrusion, the interstitial B atoms in Ti matrix significantly inhibited the diffusion of C atoms to Ti matrix (the diffusion activation energy increases from 5.82 eV to 23.41 eV by molecular dynamics simulating calculation), effectively controlling interface reaction and retaining the GNPs. Meanwhile, ultrahigh mechanical properties (1406 MPa/5.5 %) of GNPs/TA15 matrix composite were obtained, due to GNPs load transfer, TiB/TiC precipitation strengthening and B/C solid solution strengthening. This paper provides a new strategy to control the interface reaction for other GNPs/Metal matrix composites.

The introduction of alloying elements is an effective strategy to enhance the performance of titanium aluminides (TiAl). Wire arc directed energy deposition (DED) has cost advantages and high deposition rate, making it an emerging technology for fabricating TiAl alloys with promising application prospects. However, the efficient and flexible introduction of alloy elements for wire arc DED fabricated TiAl alloys is a key concern. In the present research, niobium (Nb) was selected as the alloying element, pure Ti, Al, and Nb wires were used as raw materials to introduce Nb into TiAl alloy via in-situ alloying using Triple-wire arc DED. This approach successfully fabricated the high Nb TiAl alloy Ti-45Al-8Nb and the feasibility of this method was confirmed. By comparing the phase composition, microstructure, and mechanical properties of Nb-containing Ti45Al8Nb and Nb-free Ti45Al fabricated by wire arc DED, the influence of Nb on the microstructure and strengthening mechanisms of TiAl alloys was revealed. The results indicate that Nb alloying significantly reduces internal defects, promotes the formation of the B2 phase, increases the content of gamma phase and lamellar spacing, and refines the lamellar colonies. The solid solution strengthening, grain refinement strengthening, and dislocation strengthening effects induced by Nb alloying substantially enhanced the tensile strength and elongation of the TiAl alloy. The process for fabricating ternary TiAl alloys via wire arc DED proposed in this study utilizes three pure metal wires as raw materials without relying on the expensive and difficult-to-obtain pre-alloyed materials required in traditional processes. This approach demonstrates the capability of wire arc DED in fabricating multi-component TiAl alloys with controllable compositions.

This work managed the extrusion strain path by designing various extrusion die cavities, successfully realizing the texture modification for the ZK60 magnesium alloy. The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated. Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens, but did not produce too large microstructure differences. By comparison, significant texture differences developed owing to the various extrusion die cavities, which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND. Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity. The results from the finite element analysis and the visco-plastic self-consistent model indicated that, in order to accommodate the different strain components induced by the extrusion die cavities, slip systems or tension twinning were activated differently, and this was the critical reason causing the above texture differences. One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress. Additionally, the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation, and the former generally produced the lower yield stress and the increasing stage of strain hardening rate, while the latter produced the higher yield stress and the continuous decline of strain hardening rate.

Arc-directed energy deposition (Arc-DED) of the Inconel 718 (IN718) superalloy offers distinct advantages, such as low cost and high deposition efficiency. However, these methods are plagued by problems such as poor forming accuracy, coarse microstructures, and suboptimal mechanical properties. This study introduces a laser beam as an auxiliary heat source for the arc, seeking to present a novel approach to fabricate high-performance thin-walled structures of the IN718 superalloy. By contrasting the effects of Arc-DED and hybrid laser-arc directed energy deposition (HLA-DED) on the fabrication of thin-walled IN718 superalloy components, we find that HLA-DED technology significantly improves the forming accuracy, refines the microstructure, and enhances the mechanical properties of thin-walled structures. Specifically, compared with Arc-DED, the thin walls produced by HLA-DED show an 18.39 % increase in the effective width coefficient and a 59.13 % reduction in the machining allowance. Additionally, the significantly large heat input in HLA-DED expands the remelting region, leading to a higher microhardness of the samples. Prolonged in situ heat treatment during HLA-DED promotes the dissolution of Laves phases (950 degrees C) and subsequent precipitation of gamma '' strengthening phases and MC carbides (650 degrees C). These improvements significantly enhance both the strength and plasticity of the IN718 superalloy components fabricated via HLA-DED. As a result, compared with the Arc-DED samples, the HLA-DED samples exhibit superior yield strength, ultimate tensile strength and elongation in both the horizontal and vertical directions.

In this study, an integrated polycrystalline plasticity model, referred to as the VPSC-dDRX(CA) approach, was developed for the first time by combining the viscoplastic self-consistent (VPSC) framework, discontinuous dynamic recrystallization (dDRX) mechanism, and a cellular automaton (CA), to predict the microstructure evolution of magnesium alloys during hot deformation. The model was calibrated using isothermal uniaxial compression tests on as-extruded AZ31B magnesium alloy. Temperature- and strain rate-dependent constitutive relationships were established to describe dislocation density (DD) hardening and dDRX behavior over the range of 523-673 K and 0.001-0.1 s(-)(1). Simulation and experimental results under uniaxial compression showed that higher temperatures and lower strain rates enhanced prismatic slip activity, promoted dDRX, and weakened the <0002>//CD texture. The high accuracy of the proposed multiscale framework is evidenced by grain size errors of less than 5% and texture intensity deviations under 10%. The engineering applicability of the proposed model was illustrated through simulations of multi-directional forging (MDF) and conical-die forward extrusion (CDE), which respectively revealed the path sensitivity and regional heterogeneity of microstructural evolution. The proposed model provides accurate predictions of microstructure and texture evolution under complex deformation conditions, offering a robust framework for assessing region-specific mechanical responses and guiding the design of magnesium alloy forming processes.

This study quantitatively investigates the relationship between regional yield strength and microstructure in Mg-9Gd-5Y-0.5Zr (wt.%) alloy cups formed by backward extrusion. A refined GM-HP model was developed, incorporating texture, grain boundary, and dislocation strengthening to accurately predict the compressive yield strength across different regions, accounting for microstructural heterogeneity. The microstructure exhibits significant diversity, driven by variations in the deformation path and dynamic recrystallization (DRX), transitioning from a mixed-grain microstructure with <0001>//ED texture to fully recrystallized fine grains in the corners, followed by grain coarsening in the walls. Microstructural analysis reveals that basal slip is the predominant deformation mechanism, with prismatic slip serving as a secondary contributor. The orientation factor M, strongly influenced by texture, reaches a maximum value of similar to 3.3 under the <0001>perpendicular to ED texture. Geometrically necessary dislocations (GNDs) exhibit an inverse correlation with DRX, with values ranging from 0.55 to 2.75 x 10(14) m(-2). The GM-HP model reveals that grain boundary strengthening contributes 50-70 % of total yield strength, and highlights the significant hardening of <0001>perpendicular to ED texture and GNDs. These findings provide valuable insights for optimizing the microstructural design and plastic deformation processing of magnesium alloy.