Initial Texture Research Articles

The Influence of the Strain Rate on Texture Formation During the Plane Strain Compression of AZ80 Magnesium Alloy.

Controlling microstructure and texture development is a key approach to improving the formability of magnesium alloys. In this study, the effects of the strain rate and initial texture on the texture evolution of magnesium alloys during high-temperature processing are investigated. The plane strain compression of three types of AZ80 magnesium alloys with different initial textures was assessed at 723 K and a train rate of 0.0005 s-1. Work softening was consistently observed in the stress-strain curves of all samples. However, the peak stress varied depending on the initial texture, with lower peak stress observed under conditions favoring prismatic slip. Under these conditions, the activation of non-basal slip suppressed the formation of basal texture. The texture shifted and developed parallel to the transverse direction when prismatic slip was dominant. In contrast, the activation of pyramidal slip led to the formation of a basal texture tilted by 25° from the (0001) plane. The effects of recrystallization and grain boundary migration on texture development were minimal. This study contributes to understanding the texture development mechanisms in magnesium alloys and provides insights into improving their workability and ductility through texture modification.

Tribological and mechanical behavior of AL 2014 aluminum alloy influenced by microstructure and texture evolution after equal channel angular processing

In the present study, the impact of microstructure and texture evolution on the wear and mechanical behavior of equal channel angular pressing (ECAP) of Al 2014 was examined. The average grain size of Al 2014 decreased dramatically from 101 to 6.5 microns after ECAP passes. The distribution of grain boundaries and crystallographic texture changed due to this grain refinement, significantly improving the wear and mechanical properties of the processed alloy. The enhanced wear resistance seen after ECAP resulted from low-angle boundaries (LABs) preventing fracture propagation, according to the electron backscatter diffraction (EBSD) analysis. Additionally, a notable change in texture was observed after ECAP; the initial S-rolling texture of the material, in its as-received condition, transformed into distorted Copper and A-type textures, indicating the complex strain conditions induced by the ECAP process. The ability of ECAP to improve the material's suitability for high-wear resistance applications was further demonstrated by tribological tests, which showed that the ECAP-processed Al 2014 alloy had noticeably lower wear rates than its as-received counterpart. Similarly, the mechanical results show that ECAP significantly improved the hardness and tensile characteristics.

Anisotropic compressive deformation behavior of hot-rolled Mg-3Al-0.5Ce alloy

This work investigates the anisotropic compressive deformation of hot-rolled Mg-3Al-0.5Ce alloy and correlates it with microstructure and texture. Hot-rolled alloy had elongated and equiaxed grains with long-aligned Al11Ce3 precipitates within the grain boundaries along rolling direction (RD) and basal texture along normal direction (ND). Analytical and crystal plasticity-based viscoplastic self-consistent predominant twin reorientation (VPSC-PTR) approaches were employed to simulate the flow curve and texture evolution for deeper insight into the deformation behavior. For compression direction (CD)∥to RD and transverse direction (TD), the basal texture was ∼⊥ to CD, which favored {101¯2}〈101¯1〉 extension twins (ET). The ETs nucleate, broaden and engulf the parent matrices with strain, rotating the lattice by ∼86.4∘ about 〈21¯1¯0〉 axes to a geometrically hard orientation with c-axis ∼∥toCD, leading to sigmoidal flow and increasing stage-II strain hardening rate (SHR). However, Al11Ce3 weakened the basal texture intensity, reducing the stage-II strain hardening compared to the single-phase Mg alloy investigated earlier. The presence of Al11Ce3 intermetallics delayed the ET nucleation event, which initiates at ε∼0.018. The ET fraction evolves to ∼0.85, lower than in the previous works on single phase Mg alloy. A reduction in the +ve SHR slope could be observed from ε = 0.03 to 0.06, indicating increased slip activities in this portion of stage-II. Beyond ε = 0.1, decreasing stage-III SHR was observed due to basal 〈a〉, and pyr 〈c + a〉-I and II slip activities in the ET orientation. The difference in the compressive behavior along RD and TD could not be observed due to Al11Ce3 precipitate's morphology with elongation along RD. For CD∥to ND, the compressive flow behavior was parabolic with decreasing SHR due to slip-based deformation. ET didn't form, and the texture change was negligible, with initial and final textures having basal texture ∼∥toCD, the geometrically hard orientation.

Predicting the evolution of texture and grain size during deformation and recrystallization of polycrystals using field fluctuations viscoplastic self-consistent crystal plasticity

This paper advances a recent formulation of a field fluctuations viscoplastic self-consistent (FF-VPSC) crystal plasticity model to predict not only the evolution of texture in polycrystalline metals undergoing deformation and recrystallization but also the evolution of grain size. The model considers stress and lattice rotation rate fluctuations inside grains to calculate intragranular misorientation spreads. The spreads are used for modeling of grain fragmentation during deformation and grain nucleation during recrystallization enabling the predictions of concomitant evolution of texture and grain size distributions. The evolutions of textures and grain size distributions are first simulated for commercially pure Cu undergoing severe plastic deformation (SPD) in high pressure torsion to agree well with corresponding experimental data. Next, the evolution of texture and grain size in an aluminum alloy (AA) 5182-O after simple tension and static recrystallization are predicted and compared with experiments. Finally, the predictions of texture and grain size distributions in a magnesium alloy WE43 undergoing a thermo-mechanical loading in the dynamic recrystallization regime are presented and compared with experiments. After validation, the model is coupled with the implicit finite element method (FEM) via a user-material subroutine (UMAT) in Abaqus to facilitate modeling of complex boundary conditions and geometries. The multilevel approach is referred to as FE-FF-VPSC in which every integration point embeds the FF-VPSC constitutive law, considering texture evolution and the directionality of deformation mechanisms operating at the single crystal level. FE-FF-VPSC is applied to simulate a sequence of rolling, recrystallization, and deep drawing of a circular cup of AA6022-T4. The simulated processing sequence demonstrates the versatility of the simulation framework developed in the present paper in not only predicting texture and grain size evolution and phenomena pertaining to behavior of materials but also geometrical shape changes important for the optimization of metal forming processes. To this end, the effects of initial texture and underlying anisotropy on the formation of earing profiles during deep drawing are simulated and discussed.

Evaluation and application of a multi-scale numerical model for determining subsurface drainage system design criteria in arid agriculture areas

Subsurface drainage is an effective measure for mitigating soil salinization, while few studies investigated the subsurface drainage design criteria in regional scale and its determining method and influencing factors. In this study, a multi-scale numerical model was established using SDR, MODFLOW-LGR and MT3DMS to simulate the regional groundwater and subsurface drainage. After the model was calibrated and validated by real-world data, a total of 1288 scenarios were simulated to evaluate the effect of subsurface drainage simulation method, grid size and study the influence of irrigation quantity, initial groundwater table depth (GWDini) and soil texture on subsurface drainage design criteria. The results show that utilizing the DRN package to simulate subsurface drainage led to substantial errors, with relative root mean square errors exceeding 120 %. The subsurface drainage amount simulated by SDR generally decreased with increasing grid size, because the groundwater level at the midway is averaged by a larger adjacent region. To balance simulation efficiency and accuracy, a 1 m grid size is appropriate for the SDR package in subsurface drainage simulation, with relative errors smaller than 4.8 %. The design criteria depends on the hydraulic conductivity of the first layer aquifer (Ka), followed by irrigation quantities during the winter irrigation (IWP), GWDini and irrigation quantities during the growth period (IGP). On average, for every 10 % reduction in IWP and IGP (i.e., 64 and 30.2 mm), the minimum pipe depth (MPD) increases by approximately 0.08 m and 0.03 m, respectively. For every 1 m reduction in GWDini, the MPD increases by approximately 0.13 m. When Ka is less than 0.5 m/d, there is a significant increase in MPD due to the decrease in Ka, especially at larger pipe spacing. This study provides references for accurate predictions of regional groundwater and salt dynamics, subsurface drainage and the determination of subsurface drainage design criteria.

Effect of initial texture on the formability of Zircaloy-4 sheet in stamping with FEM-VPSC modeling

Zircaloy-4 (Zr-4) sheets are widely used in nuclear industry as assembly structural parts due to its low neutron absorption cross, excellent corrosion resistance and mechanical properties. The initial texture of Zr-4 has great influence on the formability of the sheet. In this paper, the texture evolution with its related deformation mechanism have been analyzed for Zr-4 during stamping process. Finite element model (FEM) was built to achieve the strain path for various locations on the longitudinal section. Modeling accuracy has been validated with the comparison of crack location and experimental thickness distribution. The effect of initial texture on the mechanical property and forming limit curves were discussed. At last, FEM combined with visco-plastic self-consistent (VPSC) modeling was built to predict the effect of different initial texture on deformation modes for Zr-4 in sheet forming process. The results show that smaller initial Kearns factor in normal direction lead to lower stress-strain curves with higher hardening exponents (n value). The cracking strain path near punch corner followed at first plane strain path, then changing to biaxial stretching strain path. It went beyond the forming limit curves (FLC) firstly with normal Kearns factor of 0.71. With the initial normal Kearns factor decreasing to 0.68, the strain paths always remain in the safe region without exceeding FLC. Lower normal Kearns factor induced better formability for Zr-4 sheet with higher prismatic slip. It is expected that this investigation will be helpful to optimize the initial texture, which will be more appropriate for forming process.

Bending properties and deformation micromechanisms of near-α titanium alloy sheets/foils considering initial texture characteristics and size effect

Clarifying the bending deformation behaviour of metal foils is essential for meeting the lightweighting requirements of metal honeycomb structures. This study selected Ti65 alloy specimens with various thicknesses and initial α-phase textures to conduct room-temperature three-point bending experiments. A detailed comparative analysis was performed on the bending deformation behaviour of Ti65 alloy sheets and foils. It reveals that in the foil specimens, the weakening effect of surface layer grains is significant. Under the influence of size effects, the springback angle of Ti65 alloy foils with coarse α-phase grains decreases markedly. Additionally, through various methods, including global Schmid factor analysis, lattice rotation analysis, and crystal plasticity finite element method simulations, the specific relationship between α-phase texture and the bending performance of Ti65 alloy foils was thoroughly investigated. The rolling process influences the bending performance of Ti65 alloy by determining the α-phase texture. Unidirectionally rolled Ti65 alloy products exhibit a transverse α-phase texture, which predisposes them to form transverse texture α-phase macrozones during bending. In contrast, cross-directionally rolled Ti65 alloy foils possess a basal α-phase texture biased toward the transverse direction. This not only helps avoid the formation of macrozones but also ensures coordinated deformation across the foil, resulting in superior bending performance.

Texture of Hot-Compressed Metastable β-Titanium Alloy Ti5321 Studied by Neutron Diffraction.

The textures of the β- and α-phases of the metastable β-titanium alloy Ti5321 after hot deformation were investigated by neutron diffraction. A hot-rolled bar was solutionized in the β-phase field and then hot compressed above and below the β-transus temperature. The initial texture after full recrystallization and grain growth in the β-phase field exhibits a weak cube component {001}<100> and minor {112}<110> and {111}<110> components. After hot compression, a <100> fiber texture is observed, increasing in intensity with compression temperature. Below the β-transus temperature, dynamic recrystallization of the β-phase and dynamic spheroidization of the α-phase interact strongly. The texture of the α-phase is a <11-20> fiber texture, increasing in intensity with decreasing compression temperature. The mechanisms of texture formation during hot compression are discussed.

The texture evolution near the shear band and corresponding impact on the microvoid nucleation and crack propagation of Ti6242s alloys under high strain rates

This study investigates the texture evolution near the adiabatic shear bands (ASBs) and its impact of on the adiabatic shear failure mechanism, focusing on microvoid nucleation and crack propagation in Ti6242s alloy with an equiaxed α microstructure under high strain rates, using a split Hopkinson pressure bar (SHPB) for the experiments. To achieve this, the initial microstructure was used to enable the texture with the c-axis perpendicular to the loading direction. After compression, the initial texture transformed into two main texture components through different mechanisms. One texture component, aligned parallel to the loading direction, is strongly associated with the {10 1‾ 2} tensile twins, which were widely distributed near the ASBs with their c-axis are 85° to the parent grains in the initial microstructure. The other texture component, with its c-axis perpendicular to the ASB, is formed by the basal slip activation during adiabatic shear deformation. Besides, it should be noted that twinning resulted in the formation of hard grains (with the c-axis of α-grains parallel to the loading direction), increasing the number of hard-soft grain boundaries. A key finding of this paper is the presence of numerous microvoids near the ASB mainly initiated at soft-hard grain boundaries (approximately 65 %), attributed to stress concentration at the boundaries of soft-hard grains, making these boundaries potential nucleation sites for microvoids. Additionally, basal slip bands in the equiaxed α grains provide rapid channels, accelerating the crack propagation rate. This study provides new insights into refining the adiabatic shear failure mechanism under dynamic loading.

Influence of textural variability on plastic response of porous crystal embedded in polycrystalline aggregate: A crystal plasticity study

Damage evolution in polycrystalline aggregates is complicated by the intricate interplay of crystallographic orientation of the porous grain and the surrounding anisotropic matrix. Therefore, formulation of design rules and damage models for polycrystalline materials proves daunting due to relative lack of thorough understanding of the underlying heterogeneity at the mesoscale. This work explores the orientation dependent void growth in a porous crystal embedded in an anisotropic polycrystalline matrix with different initial textures. Polycrystalline face-centered cubic based aggregate is simulated within the framework of crystal plasticity finite element method. Porosity is first modeled in the form of a single pre-existing spherical void in the central grain of the randomly oriented polycrystal. One-hundred crystallographic orientations of the central grain in three-dimensional Euler space are analyzed to reveal the orientation dependent trends of the porous grain. To account for textural variability, the analysis is repeated for polycrystals exhibiting preferred textures like Cube, Brass, Copper and Goss. In this manner, interesting orientation dependent trends in basic tenets of void growth like yield strength, coalescence strain and porosity evolution are unraveled across various polycrystalline textures. To account for spatial heterogeneity as well, porosity in the central grain is then re-distributed and the aforementioned analysis is repeated for all the crystallographic orientations of the central grain embedded in polycrystals with different textures. Owing to the large amount of data thus generated, statistical analysis is invoked to identify stimulating trends and key statistical variables governing the strength and toughness. Consequently, a statistical void growth model is also presented by assessing the CP simulation results and identifying suitable distribution function governing the growth of voids in polycrystals. The modeling framework is expected to inform porous plasticity models aimed at capturing damage evolution in porous grains embedded in polycrystalline materials exhibiting topological and crystallographic anisotropy.

Initial soil moisture and soil texture control the impact of storm surges in coastal forests

Flooding and salinization triggered by storm surges threaten the survival of coastal forests. The forest root zone (top 40 cm of soil) is the most affected by surge flooding. Determining the effect of a storm surge on edaphic conditions is essential to estimate vegetation response. Pre-storm soil hydrology could mitigate or enhance the salinization effect, ultimately determining the resilience of the forest. Here we assess the influence of pre-storm soil water content and salinity on storm surge effects in coastal vegetated areas. A 1D model (HYDRUS-1D) is used to simulate saltwater infiltration from above through the unsaturated zone. Different water content and concentration scenarios, along with scenarios with variable storm surge salt concentration, storm surge height and storm surge flooding duration are considered. In soils characterized by silt and clay, the maximum salinized soil depth increases as water content increases, affecting the top 40 cm of soil, except for clay loam soil, for which only the top 20 cm are salinized. In sandy soils, the salinization process involves the entire soil column. The contribution of water content to salinization varies from 12 % to 30 % along the top 40 cm in fine soils. In fine soils, the storm-surge height also becomes relevant. A study case is presented to support the numerical results. Field data confirm that soil water content controls the salinization of the root zone in clay and silt soils. Overall, we conclude that the root zones of coastal forests with clay and silt soils and low water content are the most at risk during storm surges. These events have the potential to radically change edaphic conditions and affect ecosystems.

Texture and bendability evolution mechanism of 6063 aluminum alloy tube formed by free-bending technology employing cross-scale numerical modeling

With the improvement of application requirements, the combination of precise shape and high performance of tube components has become a burning issue. This work investigates the free-bending process of 6063 aluminum alloy tubes using cross-scale numerical modeling. The cross-scale framework integrates macroscopic finite element model (FEM) and crystal plasticity finite element model (CPFEM) through strain history. CPFEM exhibits excellent agreement with the macroscopic FEM and experimental results for both the Mises stress and texture evolution. Predictions indicate that as bending deformation increases, the volume fractions of the initial Cube texture decrease, while the Goss texture component increases. The overall texture strength continuously decreases. Meanwhile, slip mode plays a critical role in texture evolution, causing similar trends in the inner and outer bend regions. Additionally, the findings from the cross-scale simulation accurately predict the detailed texture evolution of the 6063 aluminum alloy tube under various feeding speeds. The development of Goss texture in various forming regions and the formation of substructures within Goss-oriented grains are primary factors contributing to reduced tube formability, which could illustrate the primary mechanisms for variation in tube bendability effectively. The proposed cross-scale method lays the foundation for research on complex spatial tube components as well. Moreover, cross-scale simulation facilitates the prediction of macroscopic deformation and microstructural evolution in critical regions of tube components, allowing for the optimization of bending processes based on cross-scale simulation results.

Study on microstructure evolution and deformation behavior of Mg– Zn base alloy pipes during hot bending

The strong basal fiber texture of magnesium (Mg) alloy pipes usually leads to poor secondary forming performance. In this study, Mg–2Zn-0.4Ce-0.4Mn (ZME) and Mg–2Zn-0.4Ce-0.4Mn-0.2Ca (ZMEX) pipes were prepared. Compared with the ZME pipe, the ZMEX pipe with a weaker initial texture exhibits excellent bending performance, with a peak load displacement (PLD) of 14.5 ± 0.5 mm and a total energy absorption (TEA) of 142.9 ± 1.7 J. The difference in bending performance between the two pipes is related to the deformation mechanism during hot bending. In the hardening stage, the deformation of the compression zone (CZ) of the two pipes is mainly ETW nucleation, and the overall proportion of twin grains is similar. However, in the tensile zone (TZ), the deformation of the ZME pipe is mainly prismatic slip, while the weak initial texture of the ZMEX pipe leads to the deformation dominated by both prismatic and multiple pyramidal slips, resulting in a higher hardening rate. In the softening stage, the deformation behavior in the CZ and TZ of both pipes tends to be similar. In addition, it is revealed that the softening phenomenon of both pipes after the bending displacement reaches PLD is caused by discontinuous dynamic recrystallization (DDRX) driven by high-density dislocations accumulated in the later CZ and TZ. The research on the microstructure evolution and deformation mechanism of Mg alloy pipe during bending deformation carried out in this study is of great significance for optimizing its secondary forming controllability and further expanding its application.

Topological transition to rest in the electrohydrodynamics of nematics

ABSTRACT Some nematic liquid crystals undergo electro-convective instabilities if forced by a low-frequency oscillating electric field. When the forcing amplitude is increased, a series of bifurcations occurs, which correspond to increasing disorder and reduction of the size of the electro-convective rolls. At a threshold, a transition to an electrohydrodynamic state characterised by a high density of topological defects occurs. Here, we show that in some nematic mixtures this transition is replaced by a topological transition to rest, that is, the electrohydrodynamics are quenched by the nucleation of a state that is topologically non-equivalent to the initial texture of the nematic.

Evolution and mechanism of recrystallization microstructure and texture in GH3536 superalloy foil and their influence on strength performance

To achieve isotropic strength in GH3536 foil, this study investigated the influence mechanism of initial recrystallization microstructure and texture characteristics of GH3536 superalloy foil with different cold-rolled reduction rates (referring to the reduction rate in thickness) on annealing recrystallization microstructure, including secondary recrystallization microstructure, and texture. This was studied by controlling the cold-rolled reduction rate and annealing temperature, in conjunction with microstructure and texture analysis. Meanwhile, this study clarified the dependency of strength performance on recrystallization microstructure and texture. The results of this study indicate that the Coincidence Site Lattice (CSL) grain boundaries and High Energy (HE) grain boundaries did not show significant superiorities, and were not the primary reasons for the formation of Brass ({011}<211>) and Goss ({011}<100>) textures, as well as secondary recrystallization. Instead, by controlling the cold-rolled reduction rate, the initial recrystallization stage formed a significant quantity and size superiority of α-fiber texture ({110}∥ND) in each grain size range. This led to preferential growth, and even abnormal growth of Brass and Goss grains in subsequent high-temperature annealing processes. The control of the α-deformation fiber texture was identified as the driving factor behind the formation of the initial recrystallization texture due to the cold rolling reduction rate. Cold-rolled processes with a deformation amount greater than 40 % yielded a quantity superiority of α-fiber texture shear bands and an appropriate stored energy advantage. This facilitated the nucleation and effective growth of more α grains, while suppressing the random growth of grains with γ-fiber texture ({111}∥ND). Ultimately, a quantity and size superiority was achieved in the initial recrystallization stage. The tensile strength of GH3536 foil was controlled by grain size and texture. By controlling the deformation amount to approximately 30 %, GH3536 foil was successfully produced with no pronounced orientation texture and isotropic strength.

Role of Food Texture, Oral Processing Responses, Bolus Properties, and Digestive Conditions on the Nutrient Bioaccessibility of Al Dente and Soft-Cooked Red Lentil Pasta.

The purpose of this study was to assess the impact of food texture, oral processing, bolus characteristics, and in vitro digestive conditions on the starch and protein digestibility of al dente and soft-cooked commercial red lentil pasta. For that, samples were cooked as suggested by the provider and their texture properties were promptly analysed. Then, normal and deficient masticated pasta boluses were produced by four healthy subjects, characterised in terms of their oral processing, bolus granulometry, texture and viscoelastic properties, and finally subjected to static in vitro digestion, according to the INFOGEST consensus for both adults and the older adult population. Normal masticated boluses exhibited greater saliva impregnation and lower proportions of large particles, hardness, and stiffness than deficient masticated boluses. Likewise, insufficiently masticated al dente-cooked pasta boluses caused a delay in oral starch digestion owing to the larger particles attained during food oral processing, while reduced intestinal conditions in the elderly only interfere with the release of total soluble proteins in all samples. This work evidences the importance of considering the initial texture of products, oral capabilities, processing behaviour, and physical and mechanical properties of food boluses in digestion studies, opening new prospects in designing pulse-based foods that meet the nutritional requirements of the world's population.

On surface texture evolution in abrasive flow machining

ABSTRACT Abrasive Flow Machining (AFM) is highly effective for precise surface control and finishing. The process’s material removal mechanism significantly impacts surface quality, especially in complex parts. However, little research addresses how initial micro-surface textures affect AFM outcomes. This study prepared four types of initial surface profiles and machined them using various abrasive media particle sizes. The rheology of the abrasive media was analyzed, with a custom guide restricting the fluid domain to create gradient flow changes. Both experimental and simulated one-way and two-way AFM processes were conducted. Results demonstrated that the material removal efficiency improved according to an enhanced version of Preston’s equation for flat surfaces. Initial surface textures exerted more influence on material removal than anticipated. All abrasive media sizes yielded uniform surface quality, with surface roughness improvements exceeding 80%. Larger initial surface textures experienced greater material removal. Chemical element analysis confirmed the AFM process is contamination-free.

Experimental and mechanistic investigation on the plastic anisotropic deformation behavior of α-phase titanium alloy Ti-2Al-2.5Zr

Ti-2Al-2.5Zr is widely used in piping and structural support applications, however, the rolling forming process results in anisotropic deformation during service. This behavior has implications for the manufacturing processes and structural safety assessments in engineering applications. In this study, the plastic anisotropic deformation behavior of a rolled Ti-2Al-2.5Zr plate was investigated using uniaxial tensile tests along the transverse, normal, and 45° directions. Acoustic emission, electron backscatter diffraction, and scanning electron microscopy methods were used to investigate dislocation slip and twinning mechanisms. The results indicated that different microscopic deformation mechanisms caused the significant macroscopic anisotropy of Ti-2Al-2.5Zr. The primary mechanisms involved were prismatic <a> slip, pyramidal <c+a> slip, and {10-12} extension twinning. The stress direction determined the influence of each of these mechanisms during the yielding and plastic deformation phases. Application of the visco-plastic self-consistent model established the relationship between the macroscopic mechanical responses and microscopic deformation mechanisms. It was revealed that Ti-2Al-2.5Zr achieved its optimum strength when the initial texture aligned most of the grain c-axis at angles ranging from 30° to 50° relative to the deformation direction. This finding provides a direction for the texture design of Ti-2Al-2.5Zr in engineering materials.

Study on Formability Improvement of Zr-4 Sheets Based on Texture Optimization

A positioning grid is a key clamping structure for fixing the transverse and axial positions of fuel assemblies in nuclear reactors, and it is generally prepared by the transverse stamping of a Zr-4 sheet. However, the texture formed in the processing process of Zr-4 sheets can affect formability, resulting in cracking in the stamping process. Therefore, the relationship between the formability of Zr-4 sheets and the normal Kearns factor (Fn) of basal texture was studied in this paper. The results showed that the Zr-4 sheet with an Fn equaling 0.720, prepared by an isobaric reduction rolling process, would crack in the stamping process. To avoid the cracking during stamping, the formability improvement of Zr-4 sheets based on texture optimization was discussed. By using the finite element model (FEM) and a visco plastic self-consistent (VPSC) model coupled simulation, the relationship between the initial textures and formabilities of Zr-4 sheet is established. It is found that the hardening exponents (n) decreased with increasing Fns in VPSC simulations. Meanwhile, as the Fn increases, cracks are prone to occur at the bottom corner of the stamped sheet in finite element simulation. Given the results from FEM and VPSC simulations, it is proposed that the Fn should be controlled to be less than 0.7 for preventing cracks in the sheet during stamping. Additionally, a new rolling process named non-isobaric reduction rolling was designed in which the Fn of the Zr-4 sheet is successfully reduced to 0.690. The stamping results indicate that the sheet is free of cracks under an Fn of 0.690. Therefore, texture optimization with the proposed rolling process can improve the formability of Zr-4 sheets, which effectively solves the cracking problem of Zr-4 sheets.

Migration Rules and Mechanisms of Nano-Biochar in Soil Columns under Various Transport Conditions.

Compared to traditional biochar (BC), nano-biochar (NBC) boasts superior physicochemical properties, promising extensive applications in agriculture, ecological environments, and beyond. Due to its strong adsorption and migration properties, NBC may carry nutrients or pollutants to deeper soil layers or even groundwater, causing serious environmental risks. Nevertheless, the migration rules and mechanisms of NBC in soil are still unclear. Therefore, this study employed soil column migration experiments to systematically explore the migration rules and mechanisms of NBC under various flow rates, initial soil water contents, soil depths, and soil textures. The results showed that regulated by smaller particle size differences and greater surface charges, NBC exhibited a stronger migration ability compared with traditional BC. As the soil texture transitioned from fine to coarse, the migration capability of NBC significantly improved, driven by both pore structure and interaction forces as described by the DLVO theory. The migration ability of NBC was also greatly boosted as the soil transitioned from saturated to unsaturated conditions, primarily because of preferential flow. When the flow rate increased from 70% KS to 100% KS and 130% KS, the migration ability of NBC also increased accordingly, as changes in injection flow rates altered the velocity distribution of pore water. NBC in 25 cm soil columns was more prone to shallow retention compared with 10 cm soil columns, resulting in weaker overall migration ability. In addition, through fitting of the two-site kinetic model and related parameters, the penetration curves of NBC under various variable conditions were effectively characterized. These findings could offer valuable insights for NBC's future efficient, rational, and sustainable utilization, facilitating the evaluation and mitigation of its potential environmental risks.