Search Results (240)

This study examines the mechanical, thermal, and electrical properties of copper tool electrodes processed via Equal Channel Angular Pressing (ECAP), with a specific focus on their performance in Electrical Discharge Machining (EDM) applications. A novel Crystal Plasticity Finite Element Method (CPFEM) framework is employed to model anisotropic slip behavior and microscale deformation mechanisms. The primary objective is to elucidate how initial crystallographic orientation influences hardness, thermal conductivity, and electrical conductivity. Simulations are performed on single-crystal copper for three representative Face Centered Cubic (FCC) orientations. Using an explicit CPFEM model, the study examines texture evolution and deformation heterogeneity during the ECAP process of single-crystal copper. The results indicate that the <100> single-crystal orientation exhibits the highest Taylor factor and the most homogeneous distribution of plastic equivalent strain (PEEQ), suggesting enhanced resistance to plastic flow. In contrast, the <111> single-crystal orientation displays localized deformation and reduced hardening. A decreasing Taylor factor correlates with more uniform slip, which improves both electrical and thermal conductivity, as well as machinability, by minimizing dislocation-related resistance. These findings make a novel contribution to the field by highlighting the critical role of crystallographic orientation in governing slip activity and deformation pathways, which directly impact thermal wear resistance and the fabrication efficiency of ECAP-processed copper electrodes in EDM. Full article

This study investigates the effects of multi-pass Equal-Channel Angular Pressing (ECAP) on the mechanical and corrosion properties of TC4-0.55Fe alloy through room-temperature tensile tests, electrochemical experiments, SEM, and EBSD characterization. The results demonstrate that, with increasing ECAP passes, the average grain size is progressively refined from the initial 3.8 μm to 1.8 μm after four passes. After four passes, the yield strength and ultimate tensile strength increase from initial values of 906 MPa and 939 MPa to 995 MPa and 1022 MPa, respectively, while the elongation at fracture slightly decreases to 12.0%. Electrochemical corrosion results reveal that ECAP processing significantly enhances the corrosion resistance of the TC4-0.55Fe alloy. Specifically, the two-pass specimen exhibits nearly an order-of-magnitude reduction in both corrosion rate and self-corrosion current density compared to the initial state. The simultaneous improvement in strength and corrosion resistance is primarily attributed to the synergistic effects of grain refinement, increased dislocation density, and the evolution of basal texture. Full article

This study investigates the thermal stability of fine-grained structures achieved through different severe plastic deformation (SPD) and heat treatment paths. Bulk fine-grained Al-0.1Sc-0.1Zr (wt%) alloy was produced via equal channel angular pressing (ECAP) using routes Bc or C, with aging before or after the ECAP. Electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM) analyses demonstrate excellent thermal stability of all four specimens. They maintain mean grain sizes below 5 μm after a 10 h thermal test at 450 °C, attributed to the presence of nano Al₃(Sc,Zr) precipitates within the microstructures. Route Bc in the ECAP method forms more stable high-angle grain boundaries (HAGBs) than route C. Whether aging occurs before or after the ECAP, similar microstructural changes are observed after thermal testing, allowing fine-tuning of the microstructure depending on the application or subsequent processes. Full article

This study systematically investigates the effects of aging treatment (AT) on the microstructure and properties of Cr/DLC coatings deposited via cathodic arc ion plating onto the surface of ECAP-7075 aluminum alloy. Utilizing a comprehensive approach combining performance tests (nanoindentation, nanoscratch testing, dynamic polarization analysis) with characterization tests (scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy), the synergistic effects of equal channel angular pressing (ECAP) and aging treatment(AT) were elucidated. The results demonstrate that the combined ECAP and AT significantly enhance the coating’s performance. Specifically, AT promotes the precipitation of η’ phase within the 7075 aluminum alloy substrate, increases the size of Cr₇C₃ crystallites in the Cr-based interlayer, improves the crystallinity of the Cr₇C₃ phase on the (060) or (242) crystal planes, and elevates the sp³-C/sp²-C ratio in the diamond-like carbon(DLC) top layer, leading to partial healing of defects and a denser overall coating structure. These microstructural transformations, induced by AT, result in substantial improvements in the mechanical properties (hardness reaching 5.2 GPa, bond strength achieving 15.1 N) and corrosion resistance (corrosion potential increasing to -0.698 V) of the Cr/DLC-coated ECAP-7075 aluminum alloy. This enhanced combination of properties makes these coatings particularly well-suited for high-performance aerospace components requiring both wear resistance and corrosion protection in demanding environments. Full article

This study systematically investigates the synergistic corrosion resistance enhancement mechanisms in aluminum matrix composites (AMCs) through the combined implementation of equal channel angular pressing (ECAP) and Ti₃C₂T_x MXene reinforcement. The results demonstrate that ECAP treatment significantly refines the microstructure, reducing grain sizes to an average of 8.7 µm after three passes, while improving mechanical properties such as hardness by 40.6–45.1%. Additionally, the incorporation of Ti₃C₂T_x enhances corrosion resistance by establishing a physical barrier that impedes the diffusion of corrosive mediators and prevents localized corrosion. Electrochemical tests reveal that the composite subjected to three ECAP passes exhibits the lowest corrosion current density (I_corr) and a remarkable 3.4-fold increase in charge transfer resistance (R_ct) compared to untreated material. These findings highlight the potential of synergistically integrating ECAP and Ti₃C₂T_x to develop high-performance AMCs with enhanced mechanical strength and corrosion resistance, offering significant implications for applications in marine equipment, aerospace, and new energy vehicles. Full article

The aim of this study was to evaluate the prospects of using natural fucosylated chondroitin sulfate (FCS) from the sea cucumber Cucumaria japonica as the active component of an implantable biodegradable scaffold to stimulate hematopoiesis in mice with cyclophosphamide (CPh)-induced myelosuppression. The scaffolds were based on bioresorbable Fe–Mn–C and Fe–Mn–Pd alloys after equal-channel angular pressing (ECAP). The efficiency of the developed constructs with FCS was compared with the activity of the same scaffolds loaded with recombinant human granulocyte colony stimulating factor, as well as solutions of these active compounds administered subcutaneously after the end of the cyclophosphamide (CPh) course. It was found that implantation of the Fe–Mn–C scaffold loaded with FCS most effectively stimulated hematopoiesis, providing a complex effect. This design of the developed constructs contributed to an increase in the concentration not only of leukocytes and neutrophils, but also platelets in the blood, promoted the proliferation of bone marrow cells, increasing the concentration of Ki-67(+) cells, and contributed to the restoration of the morphology of the animals’ spleen. Full article

The ECAP (equal channel angular pressing) technique plays a crucial role in enhancing the overall performance of aluminum alloys. In this study, ECAP was applied to a self-developed micro-alloyed Al-0.7Fe-0.4Mg-0.1Si-0.5Er aluminum alloy to investigate the strengthening effects of varying numbers of passes. The results show that after four ECAP passes, the alloy achieved a high tensile strength (208 MPa), yield strength (175.4 MPa), elongation after fracture (10.8%), and a relatively high electrical conductivity (57.1%IACS). The enhanced strength is primarily attributed to precipitation strengthening (${\sigma }_p$), grain refinement strengthening (${\sigma }_{gbs}$), and dislocation strengthening (${\sigma }_{dis}$). The grain refinement is a result of dynamic recrystallization (DRX) induced by severe plastic deformation. This study demonstrates that ECAP enables a significant improvement in the mechanical properties (82.3%) of the alloy while causing only a marginal reduction (2.9%) in electrical conductivity. These findings provide both technological and theoretical support for the manufacturing of high-performance conductors and other lightweight electrical structural components. Full article

The plastic deformation during equal-channel angular pressing (ECAP) can be affected by various material- and processing-related factors. For instance, the initial crystal orientation and grain size play an important role in determining the material flow, which may cause localized deformation in terms of macroscopic deformation banding. In this study, we use a continuous cast AA1080 aluminum alloy with coarse columnar grains to analyze the influence of casting texture on the local material flow during ECAP. Billets are extracted with their columnar grains inclined either in the same direction as the ECAP shear plane or opposite to it. Visio-plastic analysis is performed on split billets. The pass is interrupted halfway through the ECAP tool to accurately capture steady-state deformation conditions. Flow lines at several positions within the billet are identified based on the positions of deformed and undeformed marker points and fitted to a phenomenological model based on a super-ellipse function. For further characterization, hardness measurements, optical and electron microscopy are carried out on the ECAP-deformed samples. Significant differences in terms of local material flow and microstructure evolution regarding the resulting crystal orientation and deformation banding are observed. Our results confirm and emphasize the importance of initial grain size and texture effects for ECAP processing. Full article

This study investigates the microstructural evolution and mechanical response of an additively manufactured (PBF-LB/M) AlSi10Mg alloy subjected to severe plastic deformation via two passes of twist channel angular pressing (TCAP). Processing was conducted using Route Bc, with the first pass at 150 °C and the second at 250 °C. For the first time, the evolution from the initial hierarchical AM structure to a refined state was characterized in high-fidelity detail using a novel EBSD detector. The two-pass process transformed the initial structure into a heterogeneous, bimodal microstructure existing in a non-equilibrium state, characterized by a high fraction of low-angle grain boundaries (63%) and significant internal lattice distortion. The mechanical properties were dictated by the processing temperature: a single pass at 150 °C induced work hardening, increasing the yield strength from 450 MPa to 482 MPa. Conversely, the second pass at an elevated temperature of 250 °C promoted significant dynamic recovery. This led to a decrease in yield strength to 422 MPa but concurrently resulted in a substantial increase in ultimate compressive strength to 731 MPa. Full article

Understanding the limitations of cold-formed aluminum alloys in practice applications is essential, particularly due to the risk of substructural changes and a reduction in strength when exposed to elevated temperatures. In this study, the thermal stability of the ultra-fine-grained (UFG) structure formed by equal channel angular pressing (ECAP) at room temperature and the mechanical properties of the AlSi7MgCu0.5 alloy were investigated. Prior to ECAP, the plasticity of the as-cast alloy was enhanced by a heat treatment consisting of solution annealing, quenching, and artificial aging to achieve an overaged state. Four repetitive passes via ECAP route A resulted in the homogenization of eutectic Si particles within the α-solid solution, the formation of ultra-fine grains and/or subgrains with high dislocation density, and a significant improvement in alloy strength due to strain hardening. The main objective of this work was to assess the microstructural and mechanical stability of the alloy after post-ECAP annealing in the temperature range of 373–573 K. The UFG microstructure was found to be thermally stable up to 523 K, above which notable grain and/or subgrain coarsening occurred as a result of discontinuous recrystallization of the solid solution. Mechanical properties remained stable up to 423 K; above this temperature, a considerable decrease in strength and a simultaneous increase in ductility were observed. Synchrotron radiation X-ray diffraction (XRD) was employed to analyze the phase composition and crystallographic characteristics, while transmission electron microscopy (TEM) was used to investigate substructural evolution. Mechanical properties were evaluated through tensile testing, impact toughness testing, and hardness measurements. Full article

This paper studies the effect of reversible hydrogen alloying of the TC4 alloy on the microstructure, phase composition, and mechanical properties before and after equal-channel angular pressing. It is shown that the introduction of 0.3% hydrogen followed by quenching from a temperature of 850 °C leads to the formation of a thin-plate α″-martensite, which made it possible to implement 6 passes (ε ~ 4.2) of pressing at 600 °C. As a result of the deformation of the TC4-H alloy and subsequent thermal vacuum treatment to remove hydrogen, an ultrafine-grained structure with an average size of the α-phase of 0.15 μm was formed, which led to strengthening of the alloy to 1490 MPa with a relative elongation of about 5% at room temperature. The reasons for a more significant refinement of the grain/subgrain structure and an increase in the tensile strength of the hydrogenated alloy after equal-channel angular pressing in comparison with hydrogen-free TC4 alloy are discussed. Full article

Under the global initiative for automotive lightweighting to address climate challenges, this study investigates the microstructure evolution of steel–aluminum composites processed by hot equal-channel angular pressing (H-ECAP). Using 6061-T6 aluminum cores clad with 20 # low carbon steel tubes processed through 1–4 C-path passes (Φ = 120°, ψ = 30°), we demonstrate significant microstructural improvements. The steel component showed progressive grain refinement from 2.2 μm (1 pass) to 1.3 μm (4 pass), with substructures decreasing from 72.19% to 35.46%, HAGB increasing from 31.2% to 34.6%, and hardness increasing from 222 HV to 271 HV. Concurrently, aluminum experienced grain refinement from 59.3 μm to 28.2 μm, with recrystallized structures surging from 0.97% to 71.81%, HAGB increasing from 9.96% to 63.76%, and hardness increasing from 51.4 HV to 83.6 HV. The interfacial layer thickness reduced by 74% (29.98 μm to 7.78 μm) with decreasing oxygen content, containing FeAl₃, Fe₂Al₅, and minimal matrix oxides. Yield strength gradually increased from 361 MPa (one pass) to 372.35 MPa (four passes), accompanied by a significant enhancement in compressive strength. These findings reveal that H-ECAP’s thermomechanical coupling effect effectively enhances interface bonding quality while suppressing detrimental intermetallic growth, providing a viable solution to overcome traditional manufacturing limitations in steel–aluminum composite applications for sustainable mobility. Full article

Zn-Ag alloys are deemed extremely promising materials for manufacturing biodegradable medical implants. Nonetheless, their practical applications are still constrained by inferior mechanical properties. To tackle this issue, Zn-0.5Ag alloy was alloyed with Mg (0.2 wt.%) and processed by combined equal-channel angular pressing (ECAP) and rolling, with different rolling reductions (40%, 60%, and 75%). ECAP-processed Zn-0.5Ag-0.2Mg alloy exhibited superior mechanical properties to its as-cast counterpart. Subsequent rolling of 40% further enhances the mechanical performance of ECAP-processed Zn-0.5Ag-0.2Mg alloy, with yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) reaching 255 MPa, 309 MPa, and 52%, respectively, surpassing the application requirements. As the rolling reduction increased to 60% and further to 75%, YS and UTS declined, whereas EL rose continuously. The underlying mechanisms for the variation in strength and ductility were elucidated based on microstructure evolution analysis through optical microscopy (OM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) characterizations. Full article

Zinc (Zn)-based alloys are considered promising bioresorbable materials for intracorporeal implants due to their good biocompatibility and suitable degradation rate in physiological environments. However, their broader application is hindered by insufficient mechanical properties, which are essential for fulfilling the therapeutic function of bioresorbable implants. This study investigates the effect of severe plastic deformation on the microstructure and mechanical properties of as-cast Zn–0.1Mg (wt.%) alloy. The as-cast alloy, characterised by a coarse-grained microstructure with intermetallic phases at grain boundaries and low strength and ductility, was subjected to two passes of Equal Channel Angular Pressing (ECAP). The intense plastic deformation transformed the coarse-grained structure into an ultrafine-grained solid solution matrix. This substantial microstructural refinement led to a significant enhancement in mechanical performance. The yield strength (YS) and ultimate tensile strength (UTS) more than doubled, reaching 198 MPa and 215 MPa, respectively. Remarkably, the elongation increased from 2.2% to 187% in tensile testing. These findings confirm the beneficial effect of grain refinement and dynamic recrystallisation on the mechanical behaviour of bioresorbable Zn–0.1Mg alloy and highlight the high potential of ECAP processing for optimising the mechanical properties of Zn-based biodegradable materials. Full article

316L steel is widely used in various industries and is also one of the metallic materials used for biomedical applications because of its excellent mechanical properties, corrosion resistance, and biocompatibility. This article reports a comprehensive study on the effects of equal channel angular pressing (ECAP) and subsequent recovery treatment on the microstructure and the mechanical, tribological, and corrosion properties of 316L. The process includes an initial annealing at 1050 °C for 2 h to obtain a homogenous microstructure, ECAP at room temperature with a 120° inner angle, and subsequent recovery treatment at 340 °C for 1 h. The microstructure was investigated with an optical microscope and a transmission electron microscope. The mechanical properties were evaluated with hardness and compression tests. The corrosion behavior was analyzed with dynamic polarization tests. The wear test was performed using a scratching tester, and the volume loss was measured with a profilometer. The results of the study demonstrate that the ECAP–recovery sample exhibits improved properties compared to both the annealed sample and the ECAP sample. The corrosion tests show that the ECAP sample has a corrosion resistance higher than that of the annealed sample but lower than that of the ECAP–recovery sample. The ECAP–recovery sample shows the highest wear resistance and corrosive wear resistance among the three samples. Full article