Dynamic recrystallization behavior study of aluminum-based composites by phase field methodology with considering reinforcement particle volume fraction changing

The effect of a combined addition of boron and niobium on the dynamic recrystallization kinetics of boron‐containing micro‐alloyed low carbon steel has been studied by measuring the flow curves of three different (i.e., niobium, boron‐niobium, boron) micro‐alloyed steels at various temperatures and strain rates and by modeling the recrystallization kinetics in an Avrami expression. The results show that the recrystallization kinetics and flow stress can be modeled in a single function of temperature‐compensated strain‐rate (Z) using Avrami kinetics by applying, not the conventional t 1/2 ‐method, but recently proposed ε 1/2 ‐method. Detailed analysis of the Avrami kinetics together with secondary ion mass spectrometry (SIMS) and drag force calculation show that non‐equilibrium segregation of boron and boron‐niobium complex occurs up to 1100 °C and its intensity increases with the strain rate. The non‐equilibrium segregation decreases both the growth and nucleation rates of dynamic recrystallization by lowering the mobilities of the grain‐ and subgrain‐ boundaries. Combined addition of boron and niobium to boron‐bearing carbon steels leads to more intense segregation on grain‐ and subgrain‐ boundaries, which delays the recrystallization rate more strongly at an early stage but rather accelerates it at an intermediate stage of deformation by forming iron (boron, carbon) (Fe(B, C)) aggregates.

Although biodegradable Zn alloy fine wires are promising for staples, most exhibit inadequate mechanical properties, and current studies remain preliminary. In this work, Zn-2Cu-0.8Li (wt%) alloy fine wires (0.22 mm) for staples with outstanding mechanical properties were fabricated via hot extrusion, multi-pass drawing at room temperature and annealing. The microstructure, property evolutions and application feasibility for staples were systematically studied. The drawing process induces dramatic elongation of the β-LiZn4 matrix, accompanied by dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX). The low-angle grain boundary fractions significantly increase and the average grain sizes dramatically decrease. The η-Zn distributes as fine equiaxed grain bands due to DRX. The tensile yield strength (TYS) and ultimate tensile strength (UTS) increase from 376 MPa and 423 MPa to 596 MPa and 631 MPa, respectively, due to grain boundary (GB) and texture strengthening. Meanwhile, the deformability remains good with fracture elongation (EL) of 25.4% owing to DRV, CDRX and the presence of η-Zn. The wires annealed at 120 °C for 1 h show optimal mechanical properties (TYS: 492 MPa, UTS: 537 MPa and EL: 44.2%). The wires exhibit uniform degradation mode with a higher degradation rate of 327 μm∙year−1 than as-extruded wires due to increased GB densities. The fabricated staples show an ultimate tensile force of 1.86 N comparable to Ti staples. They can achieve satisfactory anastomosis of beagle gastric tissue, and show appropriate degradation properties in vitro and in vivo. These findings indicate that Zn-2Cu-0.8Li fine wires and staples are promising for clinical applications.

Optimizing hot workability of Al0.1CoCrFeNiRE high-entropy alloy for precision-formed components: Insights into dynamic recrystallization and deformation behavior

Synergistic strengthening induced by interfacial vortices and dynamic recrystallisation in magnetic pulse welded aluminium alloys

Synergistic effect of Gd/Y microalloying on dynamic recrystallization and hot deformation behavior of high-Mg content Al-9.7Mg-0.4Mn alloy

Investigation of hot deformation behavior and dynamic recrystallization mechanism of SiCp/Mg-Zn-Ca-Zr composite

Multi-scale interactions governing dynamic recrystallization: Coupled fragmentation of coarse T/η phases, DIP-induced MgZn2, and Al3(Sc,Zr) dispersoids in a high-alloy Al–Zn–Mg–Cu–Zr–Sc alloy

Role of deformation assisted processing in tailoring the microstructure and strength of Al–Mg–alumina composites

Abstract The hot‐deformation behavior and extrusion response of a rare‐earth–containing Mg-4Y-2Nd-1Gd-1Ag-0.5Zr alloy were systematically investigated to establish processing guidelines for high-strength magnesium components. Cylindrical billets were homogenized, subjected to isothermal compression at 350–500 °C and strain rates of 0.001–1 s −1 , and analyzed using a dynamic materials model to construct constitutive equations and hot-processing maps. The alloy exhibits an activation energy of ∼229 kJ mol −1 , close to the diffusion energy of Y in Mg, and a stress exponent n ≈ 5.0, confirming that high-temperature deformation is governed by dislocation glide and climb in the climb-controlled regime. Flow-stress curves reveal typical dynamic recrystallization (DRX) features, with higher temperatures and lower strain rates promoting extensive DRX and grain refinement. The instability regions predicted by the processing maps expand with strain from low-temperature/high-rate to high-temperature/high-rate conditions. Extrusion experiments validated the modelling results and identified an optimal processing window near 425 °C, yielding defect-free rods with a fine recrystallized grain size (∼4.4 µm), a yield strength of 289 MPa, an ultimate tensile strength of 335 MPa, and an elongation of 10.6 %. These findings provide a mechanistic basis for the design of magnesium alloys combining high strength and ductility, and demonstrate the effectiveness of processing-map-guided extrusion for rare-earth-modified Mg systems.

The large amount of strain combined with high temperature during Friction Stir Welding and Processing (FSWP) results in dynamic recrystallization and grain growth. The final properties of the processed material depend on the recrystallized grain structure. The ability to predict recrystallized microstructural features would take the FSWP modeling efforts one step closer to estimating the final weld mechanical properties. Here we present a computational framework for microstructural feature prediction based on the Discontinuous Dynamic Recrystallization (DDRX) principle considering plastic deformation, nucleation, and growth. The computed strains, strain rates and temperatures from an existing Heat Transfer and Material Flow (HTMF) model are utilized as input parameters for the DDRX model. The microstructural features such as average grain size, dislocation density, Taylor's factor, number of new grains formation and grain size distribution are predicted using the DDRX model. The grain size prediction is validated against experimentally measured grain size, demonstrating a remarkable 97% accuracy and the reliability of the DDRX model.

This investigation employs response surface methodology (RSM) and artificial neural network (ANN) model to develop an integrated optimization and prediction for the mechanical characteristics of bobbin tool friction stir welded dissimilar AA5052-H32 and AA6061-T6 alloys. The effects of rotational speed (Rs: 450–650 rpm), travel speed (Ts: 80–100 mm/min), and tool shoulder diameter (Td: 6–8 mm) on ultimate tensile strength (UTS) and microhardness (MH) were investigated through central composite design. The quadratic regression models developed using RSM exhibited excellent accuracy, with R2 values of 99.96% for UTS and 99.97% for MH. The parameters Rs: 650 rpm, Ts: 80 mm/min, and Td: 8 mm produced maximum UTS of 219.12 MPa and MH of 122.12 HV, attributed to enhanced frictional heat, grain refinement, and dynamic recrystallization within the stir zone. ANN modeling further validated the framework, showing strong correlations (R = 0.983) between experimental and predicted values. Microstructural examination under optimal conditions confirmed improved metallurgical bonding, lamellar material flow, and homogeneous precipitate redistribution. Overall, the integrated RSM–ANN framework provides robust tool for process optimization, enabling the defect-free joining of dissimilar alloys with excellent performance for automotive, maritime, and aerospace fields.

This study investigates the synergistic effects of an electropulsing (EP) and ultrasonic impact treatment (UIT) hybrid process on the mechanical and corrosion properties of D36 low-carbon steel. Conventional UIT has been shown to enhance surface hardness and induce compressive residual stress but is limited by a shallow affected depth and potential for increased surface roughness, which can exacerbate corrosion. In this work, we integrate high-energy electropulsing with UIT to overcome these limitations. The EP-UIT process leverages the combined effects of acoustoplasticity, thermal softening, and electroplasticity to achieve a significantly deeper hardened layer, extending beyond 2 mm, which is an order of magnitude thicker than that obtained by UIT alone. Microstructural analysis reveals that the process induces continuous dynamic recrystallization (CDRX), resulting in a gradient nanostructured layer with equiaxed grains near the surface and submicron ferrite grains at greater depths. Additionally, cementite dissolution and reprecipitation lead to a dual-phase microstructure comprising a supersaturated ferrite matrix and spheroidized Fe3C particles. The EP-UIT treatment also forms a dense oxide scale composed primarily of magnetite (Fe3O4) and hematite (α-Fe2O3), significantly enhancing corrosion resistance. Potentiodynamic polarization tests demonstrate that EP-UIT reduces the corrosion current density by 68% compared to UIT-treated samples, while electrochemical impedance spectroscopy confirms the improved barrier properties of the oxide layer. This innovative approach offers a promising strategy for significantly extending the service life of welded marine structures by concurrently enhancing their mechanical properties and corrosion resistance.

This study systematically investigates the microstructural features and Vickers microhardness evolution of friction stir welded dissimilar joints between rolled AA6061‐T6 and high‐pressure die‐cast AlSi10MgMn alloys. Optical microscopy revealed that the AA6061‐T6 base material contains elongated α‐Al grains (54 ± 6 µm), which recrystallized into fine, equiaxed grains within the stir zone due to dynamic recrystallization. The AlSi10MgMn alloy exhibited a characteristic layered architecture consisting of skin, eutectic band, and core regions, with α‐Al grain size decreasing from ∼6 µm in the core to ∼3 µm in the skin. Severe plastic deformation during friction stir welding (FSW) fragmented and spheroidized Si‐eutectic particles, yielding a more homogeneous phase distribution in the stir zone. Despite this grain refinement, precipitate dissolution resulted in a ∼30% reduction in Vickers microhardness relative to the base materials. Postweld direct‐aging treatments at 170°C–220°C were applied to restore mechanical uniformity, with the optimal condition of 200°C for 4 h minimizing hardness variation (ΔHV ≈ 47 HV 0. 2 ) without inducing grain coarsening. These findings provide quantitative insight into microstructural evolution and postweld aging in dissimilar FSW joints, supporting improved property uniformity for electrical vehicle battery housing applications.

This scientific research has optimized the parameters of Friction Stir Welding (FSW) for dissimilar aluminium alloys of AA2014 and AA5052 by using Response Surface Methodology (RSM) with a Box-Behnken Design (BBD). Four critical processing variables, i.e., tool rotating speed (1500-2100rpm), pin geometry (triangle, circular, square), axial load (7-10 kN), and welding speed (10-20mm/min), were systematically varied to assess their influence on ultimate tensile strength (UTS), yield strength (YS), elongation (E), and microhardness (H). Multi-response optimization using the desirability function revealed a set of favourable conditions: 1879.95rpm, square pin, 10 kN axial load, and 17.62mm/min welding speed. Under these conditions the mechanical performance of the weld showed a balance of UTS = 257.76MPa, YS = 196.96MPa, E = 4.41%, and H = 100.96 Hv with a combined desirability of 0.880. Subsequent validation experiments proved the model to be reliable, with errors in the prediction of UTS and YS less than 1.5%. Microstructural examination showed that the optimized weld had a fine equiaxed grain structure and a homogeneous distribution of Al2CuMg precipitates in the stir zone that is due to complete dynamic recrystallization and thorough material mixing. On the contrary, coarse grains, clusters of precipitates, and tunnel defects were produced by sub-optimal parameters, which correlated with inferior mechanical properties. In this research, the integrated approach of RSM-BBD-desirability approach has been shown to be effective in the optimization of FSW of this dissimilar pair of alloys to produce defect-free joints with an improved strength-hardness balance suitable for lightweight structural applications.

The ductile shear zones in northern Guangxi provide a crucial window for understanding Paleozoic collisional deformation and the tectonic evolution of the South China Block. The Jiufeng–Gandong ductile shear zone is located in the western part of the Motianling pluton in northern Guangxi. The penetrative mylonitic foliation within the ductile zone dips toward the ESE at angles of 55°–85°. Kinematic analyses indicate that the Jiufeng–Gandong ductile shear zone experienced sinistral thrust shearing. Anisotropy of magnetic susceptibility (AMS) results show that the shear zone generally strikes in an NNE direction, with a length exceeding 30 km and a maximum width of more than 2.5 km. The flattening degree (E value) of the magnetic susceptibility ellipsoid suggests that deformation within the shear zone is dominated by flattening strain, accompanied by a component of extensional strain. Quartz dynamic recrystallization mechanisms and electron backscatter diffraction (EBSD) analyses indicate that the sinistral thrust shearing occurred at deformation temperatures of approximately 350–650 °C. LA–ICP–MS U–Pb dating of zircons from a mafic mylonite yields a crystallization age of 443.0 ± 2.8 Ma. By integrating macro- and microstructural observations, magnetic fabric data, quartz EBSD fabric analyses, regional published geochronological constraints, and hydrothermal zircon U–Pb ages obtained in this study, we propose that the Jiufeng–Gandong ductile shear zone developed during Caledonian thrusting of the Cathaysia Block onto the Yangtze Block from SE to NW. Under collisional compression, the shear zone underwent medium- to high-temperature sinistral thrust shearing accompanied by dominant flattening strain. These results elucidate the geometry, strain characteristics, and tectonic regime of the Jiufeng–Gandong ductile shear zone, providing new insights into the Caledonian tectonic evolution of South China.

Abstract Molybdenum (Mo) is the most frequently utilized alloying element in Ti microalloyed steel to mitigate fluctuations in steel strength. This study is based on clarifying the microstructure evolution behavior of Ti microalloyed steel during controlled rolling and controlled cooling processes. To this end, trace amounts of Ti and Mo were incorporated into low-carbon steel to develop Ti steel and Ti-Mo steel. The thermal deformation behavior of Ti microalloyed high-strength steel was analyzed using a combination of thermal simulation experiments, transmission electron microscopy, and comparisons with C-Mn steel. The findings indicated that, at the onset of deformation, the flow stress of the experimental steel markedly increased with rising strain. As deformation progressed, the rate of increase in flow stress gradually diminished. Subsequently, due to variations in process parameters, the flow stress exhibited three distinct trends as strain increased. Adding Ti and Ti/Mo microalloying elements to C-Mn steel raises the deformation flow stress and dynamic recrystallization temperature of austenite, thus inhibiting dynamic recrystallization. This effect intensifies with higher microalloying content. The increased stress during hot deformation in Ti and Ti-Mo steels is mainly due to Ti and Mo hindering austenite recovery and recrystallization, primarily because of solute atom drag.

A novel approach for modelling the coupled effects of phase transformation and dynamic recrystallization in high-temperature deformation of dual-phase Ti6Al4V

Correlation between plastic deformation behavior and dynamic recrystallization in AZ31-0.9Nd-0.3Y magnesium alloy

Synergistic control of texture and strength-ductility balance in extruded dual-phase Mg-Li alloys via Al-mediated precipitation and dynamic recrystallization