Recrystallization Rate Research Articles

Analysis on hot deformation behavior and microstructural evolution of TA10 alloy smelted with the electron beam furnace

Abstract This article uses EB furnace to prepare TA10 alloy ingots with higher purity. Studying their hot deformation behavior and microstructure evolution can provide theoretical support for practical processes.The hot deformation behavior of TA10 alloy smelted via an electron beam furnace has been studied using thermal deformation experiments, the experiments were conducted from 800 °C to 1,050 °C, from 0.01 s−1 to 1 s−1 and a reduction to 60%. According to Arrhenius and Zener-Hollomon models, the constitutive equation can be constructed. TEM and EBSD aimed at exploring the microstructures and microstructural evolution, respectively. When deformed at the temperatures below the phase transition point, grain boundaries converted to large-angle gradually. The textural strength reduced when the strain rate increased. Besides, the recrystallization rate was relatively small, mainly dynamic recovery, and there was a tendency to turn into dynamic recrystallization. At the temperature higher than the phase transition point, the textural strength increased, the recrystallization rate was small, and the dynamic recovery was partially enhanced.

High-modulus magnesium alloy: Control of microstructure and mechanical properties via in-situ synthesis of the Al2RE phase

Magnesium, being the lightest structural metal, faces limitations in alloy development due to its inherently low elastic modulus. Therefore, this study develops high-performance, high-modulus Mg-15Gd-8Y-xAl-0.3Mn (wt.%) (x = 6, 8, 10) alloys and investigates their microstructure and mechanical properties. The findings indicate that the alloys primarily consist of Al2RE and α-Mg phases, with both the amount and size of Al2RE phase increasing as the Al content rises. After extrusion, both the grains and the Al2RE phase are refined. The increased modulus of the alloys is mainly due to the formation of the high-modulus Al2RE phase. When the Al content is 6 %, 8 %, and 10 %, the modulus of the alloys is 51.8 GPa, 53.8 GPa, and 56.1 GPa, respectively. Additionally, the Al2RE and Mg5RE phases can jointly regulate the microstructure and mechanical properties of the alloys. As the Al content increases, the amount of Al2RE phase increases, consuming the rare earth elements in the alloy and reducing the nano-precipitated Mg5RE phase. Consequently, with the increase in Al content, the recrystallization rate increases, and the recrystallized grains become larger. When the Al content is 6 %, the alloy exhibits a bimodal structure with the smallest recrystallized grains, resulting in the highest yield strength of 341 MPa. When the Al content is 8 %, the alloy has a fine, fully recrystallized structure, leading to a relatively high elongation of 9.1 %. These findings provide valuable insights for designing high-modulus magnesium alloys with optimized yield strength and elongation for structural applications.

A high-performance TRIP Mg-Sc-Zn alloy enhanced by fine grain strengthening and nano-precipitate strengthening

The Mg–Sc alloys have attracted considerable attention from researchers due to their martensitic transformation behavior. However, the relatively low yield strength limits their practical application. Thus, Zn alloying combined with annealing treatment was used to improve the mechanical properties by modulating its microstructure. Zn alloying can effectively delay the recrystallization rate and refine the grain size of the alloy. The β/α intensity ratio and grain size of β phase increase with the increasing annealing temperature. When the annealing temperature is 600 °C, the major phase is β-Mg-Sc with minor α-Mg-Sc, ScZn and Mg3Sc phases. Further increasing the temperature to 650 °C would lead to the dissolution of ScZn and Mg3Sc phases into the matrix, resulting in smaller precipitations. The Mg-Sc-Zn alloy annealed at 600 °C for 60 min owns the best comprehensive mechanical properties, with yield strength, ultimate tensile strength, and elongation of 307.2 MPa, 330.5 MPa, and 21.1%, respectively. Further TEM analysis reveals that fine grain reinforcement, precipitation reinforcement, and stress-induced martensitic transformation during tensile deformation are the main factors for the enhancement of strength and ductility in this alloy.

Concurrent measurement of strain and chemical reaction rates in a calcite grain pack undergoing pressure solution: Evidence for surface-reaction controlled dissolution

Pressure solution is inferred to be a significant contributor to sediment compaction and lithification, especially in carbonate sediments. For a sediment deforming primarily by pressure solution, the compaction rate should be directly related to the rate of calcite dissolution, transport along grain contacts, and calcite reprecipitation. Previous experimental work has shown that there is evidence that deformation in wet calcite grain packs is consistent with control by pressure solution, but considerable ambiguity remains regarding the rate limiting mechanism. We present the results of laboratory compaction experiments designed to directly measure calcite dissolution and precipitation rates (recrystallization rates) concurrently with strain rate to test whether measured rates are consistent with predicted rates both in absolute magnitude and time evolution. Recrystallization rates are measured using trace element chemistry (Sr/Ca, Mg/Ca) and isotopes (87Sr/86Sr) of fluids flowing slowly through a compacting grain pack as it is being triaxially compressed. Imaging techniques are used to characterize the grain contacts and strain effects in the post-experiment grain pack. Our data show that calcite recrystallization rates calculated from all three geochemical parameters are in approximate agreement and that the rates closely track strain rate. The geochemically inferred rates are close to predicted rates in absolute magnitude. Uncertainty in grain contact dimensions makes distinguishing between surface reaction control and diffusion control difficult. Measured reaction rates decrease faster than predicted from standard pressure solution creep flow laws. This inconsistency may indicate that calcite dissolution rates at grain contacts are more complex, and more time-dependent, than suggested by geometric models designed to predict grain contact stresses.

Eliminating the soft zone for grade 91 steel weldment via enhancing prior austenite grain size of the intercritical heat-affected zone

The soft zone is deemed unwanted for grade 91 steel weldments as it constitutes a cracking-sensitive region deleterious for long-term creep performance. In the present work, formation mechanisms of the soft zone in grade 91 steel weldments have been elucidated and an approach for its elimination has been proposed. It has been demonstrated that a soft zone forms within the intercritical heat-affected zone (ICHAZ) after post-weld tempering. Post-weld normalizing and tempering enables the elimination of the soft zone. Further analysis reveals that the ICHAZ of the as-welded specimen possesses a mixed structure, consisting of over-tempered martensite and fresh martensite with a fine prior austenite grain size. During post-weld tempering, the increase in grain size and the reduction in dislocation density are the main factors contributing to the decrease in hardness. The recrystallization rate of the ICHAZ is faster than that of other regions, resulting in a decrease in hardness from 350.8 HV0.3 to 204.6 HV0.3 and the formation of the soft zone. Increased prior austenite grain size in the ICHAZ, achieved through post-weld normalizing and subsequent tempering, facilitates the formation of tempered martensite and prevents the formation of the soft zone.

Understanding Excipient-Induced Crystallization of Spray-Dried Amorphous Solid Dispersion

This study investigates the compatibility of excipients with the model system SDI-X and their role in the induced crystallization of the amorphous compound-X in tablet formulations. We aimed to establish a straightforward and practical screening approach for evaluating excipient-induced crystallization of SDI in tablet matrices. Three methodologies—binary powder mixture, binary compact, and bilayer tablets—were employed to qualitatively and quantitatively evaluate the recrystallization of SDI-X with various excipients under accelerated storage conditions. The results demonstrated that binary compacts, providing direct physical contact between SDI-X and excipients, are superior in reflecting realistic drug-excipient contact within pharmaceutical tablets, enabling a more accurate assessment of excipient-induced crystallization for SDI-X. In contrast, the broadly used conventional binary blends can significantly underestimate this risk due to insufficient proximity. In addition, the bilayer tablets further confirmed that crystallization initiates at the contact surface between SDI-X and the excipients. The study highlighted that not only hygroscopicity but also the type of excipient and its physical contact with SDI-X significantly influence the recrystallization extent and rate of SDI-X. Interestingly, less hygroscopic diluents such as mannitol and lactose induced much higher levels of crystallization of SDIs, contrary to expectations based on moisture content alone. This suggests that the excipient type and contact surface are more critical in inducing recrystallization than just the level of moisture. The findings emphasize the need for careful excipient selection, study design, and sample preparation to enable appropriate assessments of SDI-excipient compatibility.

Effectiveness of supercooled freezing in suppressing ice recrystallization during frozen storage

Ice recrystallization often occurs during frozen food storage, an undesirable occurrence that can cause further damage to food cells and tissues. One factor that triggers its occurrence is the initial structure of the ice crystals formed during the freezing phase. During frozen storage, small ice crystals may recrystallize due to their high surface-to-volume ratio and excess free energy. In this study, the ice recrystallization of supercooled frozen tofu was evaluated during a 12-week frozen storage period and compared with that of slowly and rapidly frozen tofu. The storage temperature was at − 10 ± 2 ℃. Slow freezing at − 10 ℃ static air has produced large crystals up to 0.6 mm before storage and tended not to grow further. Rapid freezing at − 80 ℃ static air with elongated ice crystals exhibits the highest recrystallization rate, especially on the surface of the sample, where the maximum ice crystals grew from 0.23 mm before storage to 0.45 mm after 12 weeks. Supercooled freezing has produced small and homogeneous ice crystals, the largest being 0.15 mm, but their spherical shape tends to have a low affinity for recrystallization, which has allowed the crystals to maintain their size and structure during the frozen storage.

Critical condition for initiation of dynamic recrystallisation in electron beam powder bed fused Ti-6Al-4 V Alloy

Despite the unique capabilities of Additive Manufacturing (AM) processes for producing Ti components with complex geometries, the desired properties are only achievable if a holistic scheme is devised, considering the synergistic role of post-processing steps. This work aimed to enhance the applicability of metal AM products by improving the process chain in the manufacturing industry. For this purpose, the current work demonstrates a comprehensive investigation into the hot deformation of Ti-6Al-4 V (Ti64) pre-forms produced via the Electron Beam Powder Bed Fusion (EB-PBF) process focusing on the determination of critical conditions for initiating Dynamic Recrystallization (DRX) in these components. Following a sequential evaluation procedure, hot deformation experiments were carried out at temperatures ranging from 1000 to 1200 °C and strain rates of 0.001–1 s−1 to determine the critical stress and strain required for initiating DRX in Ti64 pre-forms and compare them to their wrought counterparts. In addition, a specific Finite Element Model (FEM) was coupled with DRX kinetics equations to predict the volume percentage of DRX grains during the hot deformation of the pre-forms. The analysis of flow stress curves showed a significant peak stress at low strains, which is then followed by a period of flow softening and eventually transitions into a nearly steady-state flow at higher strains. In addition, compared to their wrought counterparts, the EB-PBF samples exhibited a significantly superior flow softening behavior, as evidenced by a more significant volume fraction of DRX and faster recrystallisation rates. It was also revealed that the normalised strain for DRX initiation in the EB-PBF Ti64 and wrought one was 0.55 and 0.67, respectively. FEM results closely matched the experimental finding, confirming its reliability in providing valuable insights into microstructural evolution and offering a time-efficient alternative for process design and property optimisation, lowering dependence on trial-and-error approaches. Through a combination of experiments, numerical analysis, and finite element simulations, this study sheds light on the macroscopic deformation and microstructural transformations occurring during hot working processes.

Multiscale microstructural consideration for high strength diffusion bonding of Ti2AlNb alloy to GH4169 superalloy with (TiZrHfNb)95Al5 interlayer

A high entropy interlayer (TiZrHfNb)95Al5 was successfully designed for vacuum diffusion bonding of GH4169 superalloy to Ti2AlNb alloy. The relationships between grain size, grain boundary, lattice mismatch and microhardness, elastic modulus, shear strength and fracture behaviors were revealed. The typical microstructure was Ti2AlNb/B2/Solid solution/(Ti, Zr, Hf)2(Ni, Nb)+(Ti, Zr, Hf)(Ni, Nb) + Solid solution/(Ti, Zr, Hf)(Ni, Nb) + (Cr, Ni, Fe)ss/(Cr, Ni, Fe)ss/Cr-rich(Cr, Ni, Fe)ss/Ni-rich(Cr, Ni, Fe)ss/GH4169. With the holding time increased, the shear strength overall increased and decreased sharply, and the highest shear strength reached 384 MPa at 980 °C for 90 min. The microstructure had anisotropic crystal orientation, and the joints of Zone Ш for 90 min consisted of 92.08 % HAGBs and 7.92 % LAGBs. The residual strains and stresses decreased when the holding time increased. Meanwhile, recrystallisation appeared in Zone Ш, and the increase in the recrystallisation rate led to grain refinement. The lattice mismatch between (Ti, Zr, Hf)(Ni, Nb) and (Cr, Ni, Fe)ss phases was 25.05 %, indicating that the interface was non-coherent, and (Ti, Zr, Hf)(Ni, Nb)+(Cr, Ni, Fe)ss phases were located at an elastic modulus dramatically changed interface. Thus, the cracks easily formed in this interface and led to joint fracture. Moreover, the fracture mechanism was brittle fracture.

Microstructure Prediction of 80MnSi8-6 Steel After Hot Deformation Based on Dynamic Recrystallization Kinetics and FEM Simulation

The microstructure evolution during hot deformation of 80MnSi8-6 nanobainitic steel was investigated through hot compression tests at deformation temperatures of 900–1250°C and strain rates of 0.1–20 s−1. The flow curves revealed strain-hardening behavior at the beginning of deformation followed by softening effects caused by microstructure evolution. A Johnson–Mehl–Avrami–Kolmogorov (JMAK) model for grain growth and dynamic recrystallization was developed, and the kinetics were determined. Critical and peak strains were identified, and coefficients for the microstructure evolution models were determined using linear regression. The analysis of S-curves revealed that decreasing the temperature delays the onset of recrystallization and that the strain rate significantly effects the recrystallization rate at lower temperatures. Constitutive modeling and determination of the Zener–Hollomon parameter allowed the determination of the influence of hot processing conditions on material behavior during deformation. Microstructure analysis showed that, at higher deformation temperatures, grain growth occurs simultaneously with grain refinement. Coefficients for the JMAK model were implemented in QForm software. Simulation results were compared with experimental measurements exhibited good arrangement, which confirms the accuracy of the JMAK model in predicting the microstructure evolution. This study demonstrated how microstructure evolution modeling and FEM simulations combined can be used to predict the grain size of 80MnSi8-6 steel after hot deformation.

Unveiling the self-annealing phenomena and its effect on microstructure and texture evolution in the room temperature rolled Cu-0.13Sn-0.04Mg alloy

ABSTRACT In this study, we investigated the microstructural evolution of a Cu-0.13Sn-0.04Mg alloy that underwent heat treatment followed by room temperature rolling (RTR). Initially heat-treated specimens were rolled at room temperature (RT) with reduction ratios (RR) of 40% and 75% to perform microstructural and crystallographic textural analyses. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were utilise to examine both initial and deformed microstructures. Both exhibited heterogeneous microstructural distributions. Shear bands (SBs) existed in the initial specimen and became main sites for the nucleation of new grains during heat treatment. A denser presence of SBs was noted in the RTR specimens. Remarkably, an unusual self-annealing phenomenon was observed in these specimens, culminating in the emergence of recrystallized grains at RT. A plethora of such grains was observed in the severely deformed specimens, with numerous nucleating grains appearing proximal to the SBs or deformed grain boundaries (GBs). Time dependent microstructure evolution was observed via ex-situ EBSD technique in the compressed specimens. Formation of new grains, increase in high angle grain boundaries (HAGBs), and dislocation annihilations were observed with the progress of time. The crystallographic texture evolution in the initial specimen was predominantly influenced by the S component. At lower strains, the fractions of Copper component increased, whereas at higher strains, a greater fraction of Brass and S components were induced. Following a 40% RR, a saturation in hardness value was observed, which could be potentially attributable to an accelerated rate of RT recrystallization in the case of 75% RR.

Role of (Al, Ti) alloying and annealing temperature in precipitation, recrystallization, and mechanical properties of ferrous multi-component alloys

L12-precipitate-strengthened multi-component alloys (MCAs) possess exceptional combination of strength and ductility. However, the high production costs of L12-containing MCAs impede their industrial application. This study introduces a novel approach for designing cost-effective L12-containing MCAs by microalloying Al and Ti with a base composition of Fe50Ni30Cr20 (at%). Three types of MCAs were investigated in this study: Fe50.13Ni28.84Cr18.56Al1.39Ti1.08 (1Ti alloy), Fe46.53Ni27.32Cr19.91Al3.44Ti2.80 (3Ti alloy), and Fe48.51Ni25.93Cr15.75Al5.10Ti4.71 (5Ti alloy) (at%). An increase in the (Al, Ti) content from 1 to 3 at% accelerates the formation of L12 particles, whereas an increase in the (Al, Ti) content from 3 to 5 at% leads to the activation of the brittle B2 and D024 phases. The rapid co-precipitation of the L12, B2, and D024 phases in the 5Ti alloys substantially hinders recrystallization during annealing, whereas the 3Ti alloys exhibit the highest rate of recrystallization upon annealing at 600 and 700 °C, mainly due to the reduction in the stacking fault energy of the matrix. The 5Ti alloys exhibit the highest hardness and the lowest plasticity owing to the presence of brittle B2 and D024 precipitates. By contrast, the 3Ti alloy annealed at 600 °C, in which dense and relatively fine L12 particles precipitated, exhibits a superior combination of hardness and plasticity. This study provides insights into the composition and annealing condition-dependent precipitation, recrystallization, and mechanical properties of ferrous MCAs.

Structure and properties of starch - BaSO4 composite obtained using mechanical activation techniques

The aim of this study is to obtain and characterize starch films structurally modified by in situ precipitation of BaSO4 combined with mechanical activation of casting dispersion in a rotor-stator device. By the rheological method, it was found that the modification causes a decrease in the ability of casting dispersions to structure over time. Composite films with a filler content of 0 %–15 % (w/w) were characterized using optical and SEM microscopy, FT-IR spectroscopy, and tensile and moisture resistance testing data. The maximum increase in strength (by 70 %) and elongation at break (by 870 %) is achieved with a filler content of 5 % and 15 %, respectively. An increase in the filler content to 5 % causes an increase in starch recrystallization rate, but at concentrations above 5 % of BaSO4, it inhibits retrogradation. The films obtained by mechanical activation with optimized parameters were uniformly translucent, had lower water vapor permeability than films made from starch alone, had high flexibility, and did not warp or shrink. The developed high-performance, environmentally friendly method can be recommended for the large-scale production of starch-based composite materials.

Annealing hardening of the pre-deformed Cu-56at.%Au alloy due to retardation of recrystallization by L1o-type ordering

The evolution of the microstructure, physical and mechanical properties of pre-deformed samples of the non-stoichiometric alloy Cu-56at.%Au in the process of the L1o-type atomic ordering was studied. The duration of annealing at 250 °C ranged from 1 h to 2 months. Changes in microhardness and electrical resistivity at various stages of the disorder→order transition were found out, the microstructure was examined using a transmission electron microscope, XRD-scans and tensile tests were performed. Based on the resistometric results and XRD-analysis, the dependence of the fraction of the ordered phase vs. the annealing time was plotted. Consecutive changes in structural states observed during long-term annealing were considered through the competition between the energy of the elastic stresses, the surface energy and the energy of the dislocation structure. An abnormal increase in the strength properties of the alloy during annealing was found: the yield strength and microhardness of the initially deformed samples significantly increase (at 15 % and 30 %, respectively), at the same time there is a drop in electrical resistivity and an increase in plasticity. An attempt was made to describe the observed phenomena considering mutual effect of ordering and recrystallization. Discovered annealing hardening was explained in terms of the suppression of recrystallization by ordering, which is confirmed by the preservation of a high density of inherited dislocations in an ordered matrix and low plasticity of the annealed samples. The retardation in the recrystallization rate with an increase in the preliminary deformation strain of the alloy was discovered.

Microstructure evolution of the rolled tungsten during the current-assisted annealing treatment

Current-assisted annealing treatment (CAAT) is a promising method for adjusting the microstructure of metals. It was employed to heat treat the tungsten (W) with a rolling deformation of 90% to clarify its microstructure evolution under the action of current. The grain morphologies before and after heat treatment were observed by metallographic microscopy. Compared to traditional heat treatment, the CAATed W is easier to achieve full recrystallization with finer and more uniform grains. This indicates that the current increases the nucleation rate of recrystallization. The Johnson-Mehl-Avrami-Kolmogorov (JMAK) model was applied to describe the increase rate of recrystallization fraction. It can be calculated that the apparent activation energy of recrystallization under current is only 352.9 kJ/mol. Combined with electron backscatter diffraction (EBSD) characterization, the rolled W prefers to align along the 〈100〉 // ND orientation with the prolonging of current action time. In essence, the acceleration of recrystallization and the tendency of grain orientation are both related to the atomic migration enhanced by current. The electric current can generate an additional driving force for atomic migration, especially in regions with high electrical resistivity, where this driving force becomes more pronounced, leading to intensified atomic migration.

In situ study on the tensile deformation in high-density polyethylene/hexagonal boron nitride composite

Tensile deformation in the post processing of polymer plays a critical role in determining its mechanical properties. In this work, we investigated the structure evolution of high-density polyethylene/hexagonal boron nitride (HDPE/h-BN) composite during stretching in a wide temperature range from 25 °C to 100 °C in order to reveal the suitable post processing temperature of HDPE/h-BN composites fiber. The structure transition of HDPE crystal and the distribution of h-BN were investigated by in-situ small-angle X-ray scattering (SASX), in-situ wide-angle X-ray diffraction (WAXD) measurements, and scanning electron microscopy (SEM). The result shows that the parent HDPE crystal would be broken and recrystallize into highly oriented daughter crystal along the tensile direction when the tensile temperature (Tten) is in the range from 70 °C to 100 °C, though the recrystallization rate is low at high Tten. When Tten is low (25 °C), the crystallinity decreases continuously as no recrystallization takes place. In addition, the h-BN migrates accompany with the HDPE matrix and becomes oriented during the tensile direction. Combining the result of WAXD, SAXS, and the SEM measurement, it is concluded that the temperature of 70 °C is suitable for post processing of the HDPE/h-BN composite fiber.

Dynamic recrystallisation in Inconel®718 at creep conditions

Inconel®718 is a nickel-based superalloy primarily used in applications at high temperatures and loads. Its main characteristic is the high creep resistance due to a combination of microstructural features, mainly the presence of coherent intermetallic phases. Although the design of this type of alloy relies on controlling the distribution, nature and stability of the intermetallic phases, dislocations may play a determinant role on the creep resistance of nickel-based superalloys. This work investigates the creep resistance of Inconel®718 after two different heat treatments between 590 and 650 °C at 550 and 830 MPa stresses. After analysing the microstructure, we observe that dynamic recrystallisation happens at high temperatures and stresses, softening the material considerably. Therefore, we further develop mean-field models that predict the strain and microstructure evolutions during creep considering the size and fraction of precipitates, the dislocation densities, grain sizes and recrystallisation grade. Finally, we simulate the creep behaviour at different testing conditions and the initial microstructures and explore the robustness of the model beyond the measurement capabilities. The main conclusion is that an initial large amount of dislocations accelerates the nucleation and recrystallisation rates, decreasing the creep resistance of Inconel®718. In consequence, the material aged after forging presents lower creep resistance than the standard aged because of the larger initial dislocation density. On the contrary, the standard aged material undergo a strong reduction of the remaining dislocation density from forging during the solution treatment.

Crystallization behaviour of polyamide 4 and its effect on melting point

Polyamide 4 (PA4) has received widespread attention as a bio-based polyamide exhibiting biodegradability. However, the melting and degradation processes of PA4 occur simultaneously, making it difficult to perform thermal processing. To expand the difference between the melting point temperature (Tm) and the thermal decomposition temperature (Ttd), the crystallization and melting processes of PA4 were investigated to design strategies for regulating the crystallization. The isothermal crystallization and cold crystallization properties of PA4 were investigated with flash DSC. A special self-nucleation phenomenon which slowed the rate of recrystallization has been discovered. It confirms the significant differences in the morphology of crystals generated at differences temperatures. By controlling the crystallization process, the end-of-melt temperature (T95) was greatly reduced. Nucleation and crystal growth at different temperatures provided a low melting temperature (T95 = 246 °C), which was 20 °C lower than that for isothermal crystallization.

Effect of Electrical Resistance Heating on Recrystallization of Cold-Rolled Low-Carbon Steel

The “electron wind effect” has long been cited as a potential catalyst of solid-state transformations in metals, particularly when high current densities are involved. However, the literature exploring similar effects at lower current densities, such as those occurring during Gleeble thermomechanical simulation, remains scarce. The present work compares recrystallization activity in cold-rolled low-carbon steel during heat treatment by conventional furnace versus direct resistance heating (Gleeble). Multiple levels of cold work, annealing durations, and soak temperatures were examined, allowing for an in-depth comparison of recrystallization rates and activation energies between samples subjected to identical time–temperature profiles in the furnace and Gleeble. In addition to the expected increase in recrystallization behavior with the increases in temperature and cold-reduction levels, the use of the Gleeble system as the heating method resulted in faster initial microstructural transformation than a conventional furnace. The variability in recrystallized fractions persisted until the microstructures had saturated to their nearly fully recrystallized levels, at which point the microhardness and electron backscatter diffraction (EBSD) revealed convergence to equivalent behavior irrespective of the heating method. Analysis of the recrystallization kinetics by fitting to a JMAK relationship reflected the increased transformation activity during Gleeble treatment, with the value of the kinetic exponent also indicating greater grain growth activity at higher temperature.

Strength-plasticity-matched (GNPs+GFs)/Mg–3Zn-0.1Ymagnesium matrix composites with high modulus through liquid-phase dispersion and multistep deformation

This paper explores the production of high-modulus 3 wt%(GNPs + GFs) composites through high-energy ultrasonics-assisted semisolid stirring followed by combining multidirectional forging (MDF) and extrusion (EX) techniques. Compared to EX-alloy, the yield strength of the MDF + EX composite material was increased to ∼313 MPa, and the modulus was increased from ∼44 Gpa to ∼56.5 Gpa while retaining a higher plasticity of ∼9 %. The mechanical properties of the composites are significantly improved due to several factors. These include the grain boundary strengthening effect caused by refinement and high recrystallization rate, the Orowan strengthening effect due to dynamically precipitated nano-MgZn2 phases, and the homogeneous dispersion of GNPs and GFs.