Plastic Deformation Research Articles

Investigations on the Effects of Bonding and Forming Conditions on the Deformation Behavior of Copper-Steel Bimetallic Rods during the Cold Drawing Processes.

Metal composite parts are widely used in different industries owing to their significant improvement in material properties, such as mechanical strength, electrical conductivity, and corrosion resistivity, compared to traditional single metals. Such composite parts can be manufactured and processed in different ways to achieve the desired geometry and quality. Among various metal forming techniques, drawing is the most commonly used process to produce long composite wires or rods from raw single materials. During the drawing process of composite wires or rods, not only does the core radius ratio change, but the core or sleeve layer may also undergo necking or fracture due to excessive tensile stresses in the softer layer. In this paper, bimetallic rods with AISI-1006 low-carbon steel cores and C10100 oxygen-free electronic copper sleeves are modeled using the finite element software DEFORM. The simulation models are verified by drawing experiments. The effects of initial bonding conditions, the initial core ratio, reduction ratio, semi-die angle, drawing speed, and friction on the plastic deformation behavior of the bimetallic rods are investigated. The results indicate that the initial bonding conditions have a great impact on the deformation behavior of the billets in terms of strain distribution, material flow, residual stress, and the final core ratio. The permissible forming parameters for obtaining a sound product are investigated as well. With the aid of these analyses, the drawing process and the quality of the products can be controlled steadily.

In-situ N-doping to improve wear and corrosion resistance of a complex-concentrated alloy manufactured by directed energy deposition

In this study, the effects of in-situ N-doping on wear and corrosion resistance of a complex-concentrated alloy (CCA) prepared by directed energy deposition have been studied. After the addition of N, the wear resistance of the CCA is significantly improved (wear rate: decreasing from ∼2.92 × 10−4 mm3/N•m to ∼0.68 × 10−4 mm3/N•m). Attributed to grain refinement and solution strengthening brought by N-doping, the resistance of the matrix to plastic deformation and delamination is enhanced effectively. Besides, the in-situ N-doping helps to reduce corrosion sites and promote the formation of protective films to improve electrochemical corrosion resistance. Therefore, in-situ N-doping is an effective method to improve the wear resistance and corrosion resistance of superalloy.

Investigating the effect of rolling deformation on the electro-mechanical limits of Nb3Sn wires produced by RRP® and PIT technologies

Future high-field magnets for particle accelerators hinge on the crucial development of advanced Nb3Sn wires engineered to withstand the large stresses generated during magnet assembly and operation. The superconducting properties of Nb3Sn enable the design of compact accelerator-quality magnets above 10 T, but at the same time the brittleness and strain sensitivity of the material impose careful consideration of the mechanical limits. In addition, accelerator magnets are wound using Rutherford cables and the cabling process generates deformations in the wire that can affect its electro-mechanical performance. This paper reports on the impact of the rolling deformation on the transverse stress tolerance of high-performance restacked-rod-process (RRP®) and powder-in-tube (PIT) Nb3Sn wires. Rolling deformation was used to mimic the effect of cabling on the wire shape. Deformed samples were compared to reference round wires in term of stress dependence and irreversible limit (σ irr) of the critical current (I c) under transverse compressive loads up to 240 MPa. Experiments were performed at 4.2 K, 19 T, on resin-impregnated single wires that imitate the operating conditions in a Rutherford cable of an accelerator magnet. The results show that rolling deformation has a detrimental effect on the initial I c of PIT wires, but it does not influence the behavior of the wire under stresses above 70 MPa. On the other hand, the deformation of RRP® wires leads to an improved σ irr without affecting the initial I c. Additionally, a 2D-mechanical finite element method model of the RRP® wire was developed to investigate the impact of the wire geometry on the plastic deformation of the copper matrix, which induces residual stresses on Nb3Sn and is the main cause for the permanent reduction of I c. Based on the model results, an alternative layout of the wire was proposed that improves its stress tolerance without affecting its electrical transport properties.

Modeling of bonding pressure based on the plastic deformation mechanism of interfacial voids closure in solid-state diffusion bonding

The model of the diffusion bonding pressure was established using the analysis calculation method and further verified by the finite element analysis (FEA) and the experiments. The normalized temperature was defined as the ratio of temperature and the melting point of the base materials. And the normalized bonding pressure was defined as the ratio of the applied bonding pressure and the yield strength at the bonding temperature. The contribution of the plastic deformation to the void closure expressed a linear relationship with the normalized bonding pressure, of which the slope was 3. The relationship was appropriate in TiAl6V4, pure copper C11000, aluminium alloy AA6061, stainless steel SUS 304, and Ni-based alloy Inconel 617 using analysis calculation. The diffusion bonding pressure design range can be summarized as σn = 0.05–0.577. Subsequently, the analytic computational model was verified by FEA. The results showed that the maximum stress was concentrated in the position of the void neck. And the linear relationship between the normalized bonding pressure and the bonded ratio was also tenable. There was a stable static error existed between FEA and the analytic computational analysis. Furthermore, the experimental verification showed the verification and accuracy of the analytic computational analysis results.

Comparative Analysis of Surface Roughness and Plastic Deformation of Reciprocating Instruments after Clinical Use.

This study assessed the surface topography and plastic deformation (PD) of new and used contemporary reciprocating instruments. Twenty-six WaveOne Gold (WOG) and EdgeOne Fire (EO) instruments were photographed under magnification. The instruments were randomly assigned to a control group of new instruments preserved for surface roughness analysis (n = 6 each), or to an experimental group to shape the root canal system of a single molar (n = 20 each), making a total of four groups (WOGnew, EOnew, WOGused, EOused). Used instruments were also photographed after instrumentation. The presence of fractures was registered. Preoperative and postoperative images were randomly ordered for evaluation. Two blinded calibrated examiners evaluated the presence of PD. Inter-observer agreement was calculated with the Kappa coefficient (K = 0.89). 3D profilometry was also used for the surface roughness analysis of six randomly selected instruments from the WOGused and EOused groups. Chi-square and two-way ANOVA tests were used to, respectively, compare PD and changes in surface roughness among the groups. No instruments fractured; however, a significantly greater percentage of EO instruments suffered plastic deformation than WOG instruments (p < 0.001), (OR = 11.09 (CI 95% 2.6-56.3)). The overall surface roughness was higher for most parameters in the EO instruments (p < 0.05). Single uses of EO instruments produced significantly higher chances of PD and increased surface roughness values compared to WOG.

Nucleation-assisted microthermometry: A novel application to fluid inclusions in halite

Halite deposits have long been utilized for interrogating past climate conditions. Microthermometry on halite fluid inclusions has been used to determine ancient water temperatures. One notable obstacle in performing microthermometric measurements, however, is the lack of a vapor bubble in the single-phase liquid inclusions at room temperature. (Pseudo-) isochoric cooling of the inclusions to high negative pressures, far below the homogenization temperature, has commonly been needed to provoke spontaneous vapor bubble nucleation in the liquid. High internal tensile stress in soft host minerals like halite, however, may induce plastic deformation of the inclusion walls, resulting in a wide scatter of measured homogenization temperatures. Nucleation-assisted (NA) microthermometry, in contrast, employs single ultra-short laser pulses provided by a femtosecond laser to stimulate vapor bubble nucleation in metastable liquid inclusions slightly below the expected homogenization temperature. This technique allows for repeated vapor bubble nucleation in selected fluid inclusions without affecting the volumetric properties of the inclusions, and yields highly precise and accurate homogenization temperatures.In this study, we apply, for the first time, NA microthermometry to fluid inclusions in halite and we evaluate the precision and accuracy of this thermometer utilizing (i) synthetic halite crystals precipitated under controlled laboratory conditions, (ii) modern natural halite that precipitated in the 1980s in the Dead Sea, and (iii) Late Pleistocene halite samples from a sediment core from Death Valley, CA. Our results demonstrate an unprecedented accuracy and precision of the method that provides a new opportunity to reconstruct reliable quantitative temperature records from evaporite archives.

High thermal stability and mechanical properties of nanosized-Fe-reinforced aluminum matrix composites via deformation-driven metallurgy

Fine-grained aluminum, characterized by high performance and lightweight, is highly susceptible to grain coarsening leading to instability at elevated temperatures. The introduction of the Fe element has shown extraordinary potential to enhance thermal stability, marked by its low solubility and diffusion rate within the Al matrix. In light of this, Fe nanoparticles were exploited to reinforce fine-grained aluminum via deformation-driven metallurgy based on the principle of severe plastic deformation. The inherent mechanisms of dynamic recovery and recrystallization associated with thermo-mechanical properties facilitated the consolidation of ultrafine-grained Al–Fe nanocomposites, resulting in homogeneous dispersion both intragranularly and intergranularly of the reinforcements with an average particle size of 200.2 ± 4.6 nm. These dispersed Al–Fe nanophases with stable structures refined grains and pinned grain boundaries to hinder migration, which significantly enhanced the thermal stability of the composites. The average grain size remained substantially constant after thermal exposure at 300 °C for 100 h, with variability maintained within a 0.20 μm threshold. The mechanical properties remained substantially unchanged, exhibiting an ultimate tensile strength of 480 ± 9 MPa and elongation of 14.8 ± 0.4 %.

Heat Flow Estimation in Polymer Films during Orientational Drawing at the Local Heater.

The optimization of the process of polymer film orientational drawing using the local heater was investigated. One of the problems with this technology is that the strength of the resulting fibers differs significantly from the theoretical estimates. It is assumed that one of the reasons is related to the peculiarity of this technology, when at the point of drawing the film is heated only on one side, which creates a temperature difference between the sides of the film in contact with the heater and the non-contact sides of the film in the air. Estimates show that even a small temperature difference of just 1 °C between these surfaces leads to a significant difference in the rate of plastic deformation of the corresponding near-surface layers. As a consequence, during hardening, in the stretching region, tensile stress is concentrated on the "cold" side of the film, and this effect can presumably lead to the generation of more defects overthere. It has been suggested that defects arising during first stage of hardening, namely, neck formation, can serve as a trigger for the formation of defects such as kink bands on the "cold" side with further orientational strengthening due to plastic deformation of the resulting fibrillar structure, at the boundaries of which microcracks are formed, leading to rupture of the oriented sample. The numerical calculation of heat propagation due to heat conduction in the film from the local surface of the heater is carried out and the temperature distribution along the thickness and width of the film during drawing is found. The temperature difference in the heated layer of the film between the contact and non-contact sides with the heater was calculated depending on the thickness of the film and the speed of its movement along the heater. It was found that the most homogeneous temperature distribution over the film thickness, which is required, by default, for the synchronous transformation of the unoriented initial folded lamellar structure into a fibrillar structure, is observed only for films with a thickness of less than 50 μm. The calculation allows us to scientifically justify the choice of orientation drawing speed and optimal thickness of the oriented polymer film, which is extremely important, for example, for obtaining super-strong and high-modulus UHMWPE filaments used in products for various purposes: from body armor to sports equipment and bioimplants.

Hybridization of thermoplastic/glass fiber reinforced epoxy composites for lightweight structures

Understanding how different hybrid composite designs under flexural, interlaminar shear and fracture is the objective of this study. The hybrid composite was manufactured utilizing the hand-layup process to produce three different laminate arrangements beside the neat composite. The effects of PC integration and position through the hybrid composites were evaluated, and an analysis of the damage mechanisms was performed. The results demonstrated that incorporating the PC sheet resulted in an improvement in overall performance. Additionally, delamination was determined to be the most prevalent type of failure, followed by fiber and matrix breakage and plastic deformation of PC sheet.

Inverted Glasses As Ductile Lithium Ion Conductors for Solid State Batteries

Inorganic electrolytes for solid state batteries with Li metallic anodes must combine properties such as high ionic conductivity, chemical stability, and resistance to failure due to propagation of Li dendrites. Abundance of experimental evidence suggests that cracking of the solid electrolytes due to pressure exerted by lithium plating into the material defects is the primary source of failure [1]. This is due to inherent brittleness of the ceramic ionic conductors, i.e. their inability to reduce stress by means other than fracture. Unlike ceramics, plastic deformation in glass can be achieved via shear and (or) by densification. Both mechanisms can be operational in glasses with reduced content of glass formers relative to the content of glass modifiers – i.e. inverted glasses. Using the example of lithium phosphorous oxynitride, Lipon, we demonstrate how these two mechanisms are capable of accommodating applied stress while avoiding creation of new surfaces by cracking. We investigate the resistance to fracture in Lipon-like glasses and the underlying connection to their composition via instrumented nano-indentation, Raman spectroscopy, and numerical simulations. We observe enhancement of isochoric shear with increase of Li content, similarly to the reports of increased plasticity in sodium aluminoborate glases with high alkali content [2]. Nano-indentation demonstrates that Lipon is extremely resistant to fracture, compared to other inorganic solid electrolytes [3].[1] Porz, T. Swamy, B.W. Sheldon, D. Rettenwander, T. Fromling, H.L. Thaman, S. Berendts, R. Uecker, W.C. Carter, Y.-M. Chiang, Mechanism of lithium metal penetration through inorganic solid electrolytes. Adv. Energy Mater. 7, 1701003 (2017)[2] Sellappan, T. Rouxel, F. Celarie, E. Becker, P. Houizot, R. Conradt, Composition dependence of indentation deformation and indentation cracking in glass. Acta Mater. 61, 5949–5965 (2013)[3] Kalnaus, A. Westover, M. Kornbluth, E.J. Herbert, N.J. Dudney, Resistance to fracture in the glassy solid electrolyte Lipon. J. Mater. Research, 36, 787-795 (2021)

Electro-Chemo-Mechanical Modeling of Composite Cathodes in All-Solid-State Li-Ion Batteries

A model-based understanding can assist and accelerate developing all-solid-state batteries (ASSB). In addition to chemo-mechanical influences within electrode particles (e.g., NMC) [1-2], a solid electrolyte (e.g., argyrodites) introduces additional interfacial interactions between electrode and electrolyte phases [3-5]. The present research derives and implements a coupled multi-physics finite-element model that captures electrochemical, transport, and structural behaviors of composite electrode structures. The models incorporate concentration-dependent and anisotropic material properties that are based on previously published combinations of experiment and density functional theory (DFT). These include stiffness and fracture toughness, porosity and crystallographic orientation, and operating conditions such as charge/discharge rates and external pressure.Figure 1 illustrates predicted stresses developed during electrode manufacturing. The relatively complex cathode microstructure is based on replicating scanning electron microscopy (SEM) images [6]. The composite electrode consists of electrode, electrolyte, and pore phases (Fig. 1a). As illustrated in Fig. 1b, the ASSB synthesis process involves applying and removing high compressive pressure, which causes plastic deformation and introduces residual stresses. Figure 1c shows residual von Mises stresses near electrode-electrolyte interfaces that can be on the order of a gigapascal. The synthesis-generated residual stresses serve as initial conditions for modeling the chemo-mechanics during battery cycling.During cell operation, spatially varying Li concentrations cause material deformation and associated stresses. Figure 1d shows predicted crack nucleation and growth during operation. Depending on the stress levels, crack nucleation and growth leads to cell degradation and capacity fade. The models predict interfacial fracture and phase separations using phase-field fracture theory. In phase-field formulation, the sharp cracks are approximated as diffuse cracks using a process-zone. High values of the phase parameter ξ (Fig. 1d) represent cracked surfaces. The structural disintegration and loss of active surface areas increase the tortuous path for Li/Li-ion transport, which eventually manifests as capacity-fade.The simulations are validated using published experimental work. The modeling approach, which combines phase-field and finite-element algorithms, is implemented using the COMSOL Multiphysics software. The models are expected to inform microstructure/manufacturing design and optimal operating conditions that improve cycling performance and limit/prevent mechanical damage.[1] K. Taghikhani, P.J. Weddle, J.R. Berger, and R.J. Kee. Modeling coupled chemo-mechanical behavior of randomly oriented NMC811 polycrystalline Li-ion battery cathodes. J. Electrochem. Soc., 168(8):080511, 2021.[2] R. Xu, Y. Yang, F. Yin, P. Liu, P. Cloetens, Y. Liu, F. Lin, and K. Zhao, Heterogeneous damage in Li-ion batteries: experimental analysis and theoretical modeling. J. Mech. Phys. Solids, 129, 160, 2019.[3] K. Taghikhani, P.J. Weddle, R.M. Hoffman, J.R. Berger, and R.J. Kee. Electro-chemo-mechanical finite-element model of single-crystal and polycrystalline NMC cathode particles embedded in an argyrodite solid electrolyte. Electrochim. Acta, 460:142585, 2023.[4] A. Bielefeld, D.A. Weber, R. Rueß, V. Glavas, and J. Janek. Influence of lithium ion kinetics, particle morphology and voids on the electrochemical performance of composite cathodes for all-solid-state batteries. J. Electrochem. Soc., 169(2):020539, 2022.[5] P. Minnmann, F. Strauss, A. Bielefeld, R. Ruess, P. Adelhelm, S. Burkhardt, S.L. Dreyer, E. Trevisanello, H. Ehrenberg, T. Brezesinski, F.H. Richter, and J. Janek. Designing cathodes and cathode active materials for solid-state batteries. Adv. Energy Mater., 12(35):2201425, 2022.[6] C. Doerrer, I. Capone, S. Narayanan, J. Liu, C.R.M. Grovenor, M. Pasta, and P.S. Grant. High energy density single-crystal NMC/Li6PS5Cl cathodes for all-solid-state lithium-metal batteries. ACS Appl. Mater. & interfaces, 13(31):37809–37815, 2021. Figure 1

Effect of processing sequences in multi-pass friction stir processing on microstructure, microtexture and microhardness of 6063 aluminum alloy

ABSTRACT Single and double direction stir processing sequences were employed and investigated by fixing all other FSP parameters. Optical microscopy (OM) was utilised to assess the size and geometry of the processed zone. EBSD was also employed to evaluate the microstructure and microtexture development in different regions of the processed zones. In addition, Vickers microhardness measurements were made to evaluate the hardness evolution across the processed zone for the two processing sequences. The results show that using a single direction processing sequence is preferable due to better grain refinement, mainly in all regions of the processed samples. Gradual improvement was observed in microhardness with each additional pass, stronger refinement, and homogeneous grains in the processed regions (stir and overlapping zones). In the first pass’s stir zone (SZ), the microhardness is approximately 42.5 Hv, while it increases to an average of 43.4 Hv in SZ2 of the second pass and 44.3 Hv in SZ3 of the third pass. Furthermore, more resistance to plastic deformation (slip) and lower intensity of heat distribution when compared to the double direction. Therefore, the application of a single direction processing sequence can be beneficial in the welding of such aluminium alloys.

Simulation and Algorithmic Optimization of the Cutting Process for the Green Machining of PM Green Compacts.

Powder metallurgy (PM) technology is extensively employed in the manufacturing sector, yet its processing presents numerous challenges. To alleviate these difficulties, green machining of PM green compacts has emerged as an effective approach. The aim of this research is to explore the deformation features of green compacts and assess the impact of various machining parameters on the force of cutting. The cutting variables for compacts of PM green were modeled, and the cutting process was analyzed using Abaqus (2022) software. Subsequently, the orthogonal test ANOVA method was utilized to evaluate the significance of each parameter for the cutting force. Optimization of the machining parameters was then achieved through a genetic algorithm for neural network optimization. The investigation revealed that PM green compacts, which are brittle, undergo a plastic deformation stage during cutting and deviate from the traditional model for brittle materials. The findings indicate that cutting thickness exerts the most substantial influence on the cutting force, whereas the speed of cutting, the tool rake angle, and the radius of the rounded edge exert minimal influence. The optimal parameter combination for the cutting of PM green compacts was determined via a genetic algorithm for neural network optimization, yielding a cutting force of 174.998 N at a cutting thickness of 0.15 mm, a cutting speed of 20 m/min, a tool rake angle of 10°, and a radius of the rounded edge of 25 μm, with a discrepancy of 4.05% from the actual measurement.

Transient Chemo-Mechanical Model of Lithium Plating Impacted by External Pressure

To meet the ever-growing need for high capacity, fast-charge batteries, lithium anodes have been considered a direct upgrade to previous commercial anode materials thanks to their high gravimetric density and low coulombic efficiency. However, their implementation into crucial applications such as electric vehicles has been hindered by safety issues during and at the end of their operational lifetime. Over hundreds of cycles, nonhomogeneous plating and stripping of lithium on the anode surface encourages the growth of dendrites, which eventually lead to capacity loss, cell failure, and fire. The application of stack pressure has been found to mitigate dendrite growth to an extent; however, the impacts of long-term pressure application on lithium deposition, and subsequent lithium plastic deformation and creep, are not well understood. In this work, we present a novel method for accurately modeling the interplay between mechanical deformation and electrochemical deposition. We develop a 3D, finite-element, transient model of lithium plating and stripping at the mesoscale. A stack pressure is applied to a lithium anode in contact with a polymer separator, and the electrochemical response to an applied current density is evaluated. The lithium protrusion is then reshaped to model incremental plating or stripping, thus simulating the cumulative interfacial movement over a full charge-discharge cycle. Mechanical complexities of the materials, such as lithium plastic deformation and separator porosity, are accounted for. The interfacial response is studied with respect to applied stack pressure and assumed lithium yield strength. Through this work, the impacts of stack pressure on dendrite growth at the microscale are explored. The lithium yield strength assumption is found to be crucial for accurately predicting deposition behavior.Supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525.

Hot Deformation Characteristics and Dynamic Recrystallization Mechanisms of a Semi-Solid Forged AZ91D Magnesium Alloy.

Magnesium alloys show great promise in high-speed transport, aerospace, and military technology; however, their widespread adoption encounters challenges attributed to limitations such as poor plasticity and strength. This study examines the high-temperature deformation of semi-solid forged AZ91D magnesium alloy through a combination of experiments and simulations, with a focus on comprehending the influence of deformation conditions on dynamic recrystallization (DRX). The findings disclose that conspicuous signs of DRX manifest in the yield stress curve as strain increases. Additionally, decreasing the strain rate and temperature correlates with a reduction in both yield stress and peak strain, and the activation energy is 156.814 kJ/mol, while the critical strain and peak strain remain relatively consistent (εc=0.66208εp). Microstructural changes during high-temperature deformation and the onset of DRX are thoroughly examined through experimental methods. Moreover, a critical strain model for DRX and a predictive model for the volume fraction of DRX were formulated. These equations and models, validated through a combination of experiments and simulations, serve as invaluable tools for predicting the mechanical behavior and microstructural evolution, which also establishes a foundation for accurately predicting the deformation behavior of this alloy. By analyzing the hot deformation characteristics and dynamic compression mechanism of the newly developed semi-solid forging AZ91D magnesium alloy, a numerical simulation model can be effectively established. This model objectively reflects the changes and distributions of stress, strain, and rheological velocity, providing a scientific basis for selecting subsequent plastic deformation process parameters and designing mold structures.

Modeling Strain Hardening of Metallic Materials with Sigmoidal Function Considering Temperature and Strain Rate Effects.

This study uses a sigmoidal function to describe the plastic strain hardening of metallic materials, considering temperature and strain rate effects. The effectiveness of this approach is evaluated and systematically compared with other hardening laws. Incorporating temperature and strain rate effects into the parameters of this sigmoidal-type hardening law enables a more precise description and prediction of the plastic deformation of materials under different combinations of temperature and strain rate. The temperature effect is coupled using a simplified Arrhenius model, and the strain rate effect is coupled with a modified Johnson-Cook model. The sigmoidal-type hardening law is integrated with an asymmetric yield criterion to address complex behavior, such as anisotropy and strength differential effects. The calibration and validation of the constitutive model involve examining uniaxial tensile/compressive flow curves in various directions and biaxial tensile/compressive flow curves for diverse metallic alloys, proving the proposed model's broad applicability.

Optimizing release properties of tablets from Spondias mombin spray-dried leaves extract using dry and melt granulation

This study aimed to investigate the efficacy of conventional dry granulation (slugging) and twin-screw melt granulation (TSMG) as downstream processing methods to enhance the technological properties, such as flowability and tabletability, of spray-dried plant extracts (SDE). A hydrophilic (Polyethylene glycol 6000-PEG) and a lipophilic binder (glyceryl dibehenate-GBE) were explored for the melt granulation process. Compression behavior and powder rheological properties of SDE and its granules were investigated. Compression analysis by in-die Heckel analysis explained the SDE's poor mechanical properties resulting in poor compact integrity in addition to the poor flow properties of the SDE. Despite the success of granulation strategies to improve the material's flowability and tabletability, the TSMG granules exhibited better performance than slugged granules. Regarding formulation, the lipophilic binder facilitated greater plastic deformation than the hydrophilic binder, enhancing the release of formulations across different profiles from controlled release, adjusting the granules quantity, to immediate-release tablets containing either brittle or plastic fillers. In conclusion, TSMG combined with a lipophilic melt binder emerged as a promising technology for overcoming the challenges of poor tabletability and modifying the release profile of ellagitannin from SDE.

Effect of low-temperature plasma nitriding on the sliding wear behavior of 17–4PH stainless steel in high temperature water

Plasma nitriding significantly enhances the tribological performance of 17–4 precipitation hardening (PH) stainless steel. However, the wear resistance of plasma-nitrided 17–4PH stainless steel in high temperature water remains unpredictable due to the complex interaction between wear and corrosion under such conditions. In this study, we conducted a wear test on nitrided 17–4PH stainless steel in high temperature water to evaluate its wear behavior. Our findings demonstrate that nitriding treatment improves wear resistance. Additionally, the wear mechanism shifts from delamination wear to oxidational wear after nitriding. The interaction between wear and corrosion was revealed. The subsurface of the worn scar undergoes plastic deformation, which accelerates corrosion. However, the oxide scale formed by corrosion can act as a lubricant to mitigate wear. For non-nitrided specimen with lower hardness, delamination cracks initially form in the subsurface, with the crack surfaces subsequently oxidizing and filled with debris. Material loss results from the peeling of the delamination. In contrast, for nitrided specimens with higher hardness, the subsurface of the worn scar is composed of an oxidation layer that detaches under mechanical wear, leading to material loss.

Mechanical response and plastic deformation in single- and dual-phase polycrystalline FeNiAl alloys: molecular dynamics analysis

Mechanical response and plastic deformation in single- and dual-phase polycrystalline FeNiAl alloys: molecular dynamics analysis

Formation of Symmetric Gradient Microstructure in Carbon Steel Bars

In recent years, severe plastic deformation has attracted the most attention as a way to improve the mechanical properties of steel bars. Obtaining ultrafine grains and nanostructures in such bars leads to a strong increase in strength properties but strongly reduces their plastic properties. This study shows that the formation of a gradient microstructure allows simultaneous improvement in the strength and plastic properties of carbon steel bars, taking into account the symmetry of the microstructure distribution from the center of machining. A new combined technology is proposed to obtain such a microstructure. This technology consists of drawing bars from medium carbon steel on a radial-displacement rolling mill and carrying out subsequent drawing. Steel bars with a diameter of 30 mm were strained in three passes to a diameter of 16 mm at room temperature. The results show that the average value of microhardness in the center, neutral, and surface areas for the three straining cycles were 1890 MPa, 2335 MPa, and 2920 MPa, respectively. This symmetrical distribution of microhardness confirms the gradient microstructure. Strength characteristics also increased almost twofold: the yield strength increased from 330 to 735 MPa, and the ultimate strength increased from 600 MPa to 1025 MPa. Relative elongation decreased from 18 to 14 MPa, and relative reduction decreased from 40 to 31%, but remained at a fairly good level for AISI 1045 steel. The validity of all results was confirmed through numerous experiments using a set of traditional and modern research methods, which included optical, scanning, and transmission microscopy. EBSD analysis allowed precise positioning of the field of vision for studying microstructural changes across the entire bar cross-section. All of these methods used together, including tensile testing of the mechanical properties and the fractographic method, allow us to assess changes in microhardness and the reproduction of results.