Yield Asymmetry Research Articles

Financing the capital-constrained farmer under random yield and investment information asymmetry: bank credit versus trade credit

PurposeFinancing the capital-constrained farmers to facilitate the production of agri-products is one of the greatest challenges facing the farming supply chain in the developing countries. In this study, we investigate the optimal financing scheme for the farming supply chain under random yield and investment information asymmetry environment to support rural economic development.Design/methodology/approachWe analyze a stylized model of farming supply chain where the capital-constrained farmer produces and sells agri-products through the agribusiness firm, and investigate the optimal financing scheme incorporating the investment information asymmetry and the challenge of yield uncertainty.FindingsThe results show that there is no one financing scheme equilibrium dominates for all situations, the financing scheme equilibrium is affected by the bank’s supervision cost to monitor the farmer’s moral hazard behavior, the variance of random yield and the farmer’s initial capital. The preference of the financing scheme for the agribusiness firm may be different from that for the farmer. The agribusiness firm might suffer from overfinancing problem under trade credit financing when the bank’s supervision cost is larger and the farmer’s own initial capital is lower; the higher variance of random yield will flare up the effect.Practical implicationsThis study sheds light on the choice of financing scheme under random yield and investment information asymmetry environment. This problem is particularly important for developing economies. Financing the capital-constrained farmers not only increases supplies of food and industrial raw materials, but also reduces poverty. The findings provide managerial implications for practitioners for how to leverage different financing scheme to support rural economic development.Originality/valueThis study develops new theoretical model for farming supply chain financing incorporating the challenge of yield uncertainty and investment information asymmetry, the two prominent factors that would impact the financial risk significantly. We analyze the equilibrium under both bank financing and trade credit financing schemes, and the results suggest that the financing scheme equilibrium is affected by the bank’s supervision cost to monitor the farmer’s moral hazard behavior, the variance of random yield and the farmer’s initial capital. The agribusiness firm might suffer from overfinancing problem under trade credit financing.

Effect of Loading Direction on Tensile-Compressive Mechanical Behaviors of Mg-5Zn-2Gd-0.2Zr Alloy with Heterogeneous Grains

The tension-compression yield asymmetry caused by the strengthening of Mg-Zn-Gd-Zr alloy due to extrusion deformation is an important issue that must be addressed in its application. In this study, the effects of loading direction on the tensile and compressive mechanical behaviors of Mg-5Zn-2Gd-0.2Zr alloy were systematically investigated. As the loading angle (the angle between the loading direction and the extrusion direction) increases from 0° to 30°, 45°, 60° and 90°, the tensile yield strength decreases more significantly than the compressive yield strength. Consequently, the tension-compression yield asymmetry is gradually improved. Additionally, the ultimate compressive strength decreases more markedly than the ultimate tensile strength with the increment of the loading angle. In tensile tests conducted at 0°, 30° and 45°, two distinct stages of decreasing strain hardening rates are typically observed. For the 60° and 90° tensile tests, one unusual ascending stage of strain hardening rate is observed. For all compressive tests, three stages of strain hardening are consistently noted; however, the increment in strain hardening rate caused by {10–12} extension twinning decreases with the increasing loading angle. A model combining loading angle and Schmid factor distribution was established. The calculated results indicate that the dominant deformation modes during the yielding process also vary significantly with the loading conditions. This clarification highlights the differences in yield strength variations between tension and compression. Finally, an analysis of the plane trace and crack propagation direction near the fracture surface reveals the fracture mechanisms associated with tensile and compressive tests at different loading directions. This study promotes understanding of the mechanical behaviors of Mg-5Zn-2Gd-0.2Zr alloy under different loading directions, and helps to thoroughly elucidate the anisotropic effects of texture on the mechanical properties of magnesium alloys.

Enhancing Strength and Reducing Yield Asymmetry in Extruded AZ91 Alloy through Combined Ca and Sr Additions

Enhancing Strength and Reducing Yield Asymmetry in Extruded AZ91 Alloy through Combined Ca and Sr Additions

A novel sustainable AZ31 based Mg matrix composite reinforced with recycled IN718 powder for circular materials economy

The pursuit of sustainable practices in manufacturing has sparked an increased interest in recycling and reusing materials to reduce waste and environmental effect. One interesting technique is incorporating recycled materials to develop advanced composite materials. In this study, we focus on utilizing recycled Inconel IN718 powders as reinforcement particles in AZ31D. Powders of IN718 finer than 37 μm, developed from machining chips through high energy ball milling process, are infused into AZ31 through friction stir processing (FSP), enabling a circular economy practice in advanced material development. The resulting composite material is evaluated for its microstructure and mechanical performance. Microstructural study reveals a uniform distribution of reinforcement particle inside the matrix throughout the processed zone. Strong interfacial bonding between the matrix and reinforcement, and the addition of dispersion strengthening mechanisms helped reducing the tension/compression yield asymmetry problem. The study highlights the use of recycled materials in composites to achieve sustainability in manufacturing.

Plastic deformation behavior of Mg–8Li dual phase alloy during multi-directional compression

The Mg–8Li dual phase alloy was deformed by multi-directional compression with different passes. Microstructure evolution of deformed Mg–8Li alloy was analyzed by electron backscatter diffraction. X-ray diffraction profile was used to calculate the dislocation density in α-Mg and β-Li phase to reveal the quantitively change trend under different compression passes. The mechanical properties were assessed through tensile and compressive tests. The Mg–8Li alloy exhibited optimal mechanical properties when compressed with 12 passes (sample 12MDC), with a compression yield strength of 183.1 MPa and a tensile yield strength of 124.2 MPa. The improved mechanical properties in sample 12MDC were attributed to an increase in {10 1‾ 2} twin and {101‾ 3}-{101‾ 2} double twin boundaries, along with the presence of sub-grain boundaries and a reduced grain size in the α-Mg phase. Additionally, the inconsistent results between microhardness and dislocation density calculation manifests the uneven distribution of dislocations in β-Li phase. Broken α-Mg phase brings more phase interface to relieve the strain in β-Li phase, which results to a decreased dislocation density in sample 12MDC (1.19 × 1011/m2). Results show that weaken tension-compression yield asymmetry and more even distribution of dislocation in both phases could be achieved when the compression passes increases to 12.

Chilling at grain filling stage reduced rice grain protein content: An experimental and modeling study

Climate change has increased the trend in the intensity of global extreme weather events, including chilling. Nitrogen is one of the most essential nutrients for rice growth and development. Chilling will limit the uptake and translocation of nitrogen and the formation of grain protein in rice plants. The experiment conducted in the climate chamber with chilling stress applied at the grain filling stage revealed different effects on protein concentration in aboveground organs and caused asymmetry in grain protein contents (GPC) and grain protein yield (GPY). Chilling stress applied during the grain filling stage reduced the accumulation rate of rice grain protein by inhibiting the nitrogen uptake and the translocation from vegetative organs to grains, which resulted in a 35 % decrease in grain nitrogen accumulation and a 92 % increase in vegetative organs during grain filling. Consequently, the average nitrogen harvest index is reduced by 12 %. Nitrogen accumulation was severely affected when cooling degree days (CDD) ≥ 70 °C days. As the chilling intensity increased, the decrease of GPY was more significant than that of GPC. Moreover, we improved the grain temperature-nitrogen uptake function under chilling stress based on the relationship between CDD and the reduction in rice grains. By comparing the improved function and the modules in the existing crop model using the datasets from open field and artificial control experiments, we demonstrated that the current research on quantifying rice nitrogen uptake at extreme temperature stress needed further improvement. The effects of environmental stress on grain nitrogen accumulation are complex. Future studies should pay more attention to the ability of extreme temperature stress to affect nitrogen accumulation in various rice organs.

Developing Zn-2Cu-xLi (x < 0.1 wt %) alloys with suitable mechanical properties, degradation behaviors and cytocompatibility for vascular stents

Biodegradable Zn alloys show great potential for vascular stents due to their moderate degradation rates and acceptable biocompatibility. However, the poor mechanical properties limit their applications. In this study, low alloyed Zn-2Cu-xLi (x = 0.004, 0.01, 0.07 wt %) alloys with favorable mechanical properties were developed. The microstructure consists of fine equiaxed η-Zn grains, micron, submicron-sized and coherent nano ε-CuZn4 phases. The introduced Li exists as a solute in the η-Zn matrix and ε-CuZn4 phase, and results in the increase of ε-CuZn4 volume fraction, the refinement of grains and more uniform distribution of grain sizes. As Li content increases, the strength of alloys is dramatically improved by grain boundary strengthening, precipitate strengthening of ε-CuZn4 and solid solution strengthening of Li. Zn-2Cu-0.07Li alloy has the optimal mechanical properties with a tensile yield strength of 321.8 MPa, ultimate tensile strength of 362.3 MPa and fracture elongation of 28.0 %, exceeding the benchmark of stents. It also has favorable mechanical property stability, weak tension compression yield asymmetry and strain rate sensitivity. It exhibits uniform degradation and a little improved degradation rate of 89.5 μm∙year−1, due to the improved electrochemical activity by increased ε-CuZn4 volume fraction, and generates Li2CO3 and LiOH. It shows favorable cytocompatibility without adverse influence on endothelial cell viability by trace Li+. The fabricated microtubes show favorable mechanical properties, and stents exhibit an average radial strength of 118 kPa. The present study indicates that Zn-2Cu-0.07Li alloy is a potential and promising candidate for vascular stent applications. Statement of significanceZn alloys are promising candidates for biodegradable vascular stents. However, improving their mechanical properties is challenging. Combining the advantages of Cu and trace Li, Zn-2Cu-xLi (x < 0.1 wt %) alloys were developed for stents. As Li increases, the strength of alloys is dramatically improved by refined grains, increased volume fraction of ε-CuZn4 and solid solution of Li. Zn-2Cu-0.07Li alloy exhibits a TYS exceeding 320 MPa, UTS exceeding 360 MPa and fracture EL of nearly 30 %. It shows favorable mechanical stability, degradation behaviors and cytocompatibility. The alloy was fabricated into microtubes and stents for mechanical property tests to verify application feasibility for the first time. This indicates that Zn-2Cu-0.07Li alloy has great potential for vascular stent applications.

Effect of rolling reduction on microstructure and tension-compression yield asymmetry of rolled AZ31 magnesium sheet

Magnesium (Mg) alloys have been receiving significant applications in automotive and aerospace industries owing to its high strength-to-weight ratios. Approximately 30 % (by weight) of material used in automobiles are in the form of sheet metal. Therefore, in the present work AZ31 magnesium (Mg) alloy was hot rolled with different reduction ratios to produce Mg sheet. The results revealed that employing a 40 % reduction per pass led to a remarkable 92 % reduction in thickness, outperforming the 82 % reduction achieved with a 20 % reduction per pass, along with fine grain of 8 μm. Investigation has been conducted on the relationship between grain size and its impact on the tension-compression yield asymmetry in Mg sheet. This investigation unveiled that the suppression of {101‾2} extension twinning mode of deformation due to the back stress imposed by the simultaneous action of grain boundaries and twin overlap, effectively minimizing the asymmetry from 2.11 (as received AZ31 alloy) to 1.13 (5th pass rolling sheet). The study extensively explored the underlying mechanisms governing the yield asymmetry behavior of AZ31 Mg sheets. These mechanisms included strain hardening tendencies, Schmid Factor, and KAM (Kernel Average Misorientation) assessment, all of which were interconnected with microstructural attributes.

Resonances in electron scattering from H2 around the H(2l) + H−(1s2) dissociation limit

We have performed high-level R-matrix scattering calculations to identify and characterise the resonances potentially involved in dissociative electron attachment (DEA) of H2 at around 14.5 eV. DEA experiments (Krishnakumar et al 2018 Nat. Phys. 4 149) indicate an asymmetric production of H− around this scattering energy that can only be explained if more than one resonance is involved in the process. The theoretical description of the anion distribution requires accurate data (energy and lifetime) for the resonances involved, currently missing from the literature. We attempt to provide these data for all the resonances identified in the appropriate energy range for bond lengths 1.1 a 0 to 4.0 a 0. Our resonance results are insufficient to confirm the validity of a simple model of anion yield asymmetry used to reproduce the experimental results.

Asymmetric tension-compression mechanical behaviors of extruded Mg-4.58Zn-2.6Gd-0.18Zr alloy with double-peak fiber texture

To clarify asymmetric mechanical behaviors of the extruded Mg-4.58Zn-2.6Gd-0.18Zr alloy during room temperature tension and compression, the evolution of microstructure, texture and strain hardening rate were systematically investigated when loading along the extrusion direction (ED). The results found that the as-extruded alloy exhibited <101̅0>-<112̅0> double-peak fiber texture, leading to obvious tension compression yield asymmetry and compressive yield plateau. Fiber texture kept stable and only texture intensity gradually decreased with the increasing tensile strain, while fiber texture was exhausted due to the extension twinning and <0001> texture component was aggravated with the increasing compressive strain. Moreover, twinning parts within grains with <101̅0> fiber texture was re-oriented to the c-axis paralleling to the ED, and that in <112̅0> fiber texture deviated about 30° away from the ED. This soft orientation would be finally rotated to the <0001> paralleling to the ED under the action of basal <a> slip, explaining why the <0001> pole dispersed at first and then concentrated with the increasing compressive strain. Three stages of strain hardening rate were both observed for tensile and compressive tests, while increment of Stage II was only observed under compression. Stage II in compression could be further divided into two parts with different slopes. Such phenomenon was seldom reported in Mg alloys, which was caused by different propagation and re-orientation of extension twinning in double-peak fiber texture, and weakened the effect of twin lamella segmentation with the increasing compressive strain. Findings in this work given us a better understanding of asymmetric tensile-compressive mechanical behaviors of extruded Mg alloys with double-peak fiber texture.

Evolution of bimodal-structure and achieving ultra-high yield strength in the as-extruded ZK70 alloy via Gd addition

Achieving ultra-high tensile yield strength over 400 MPa in RE modified Mg–Zn-based alloys using conventional thermomechanical processing is a challenging task. In this study, we successfully produced a Mg–7Zn–2Gd–0.5Zr (wt. %) alloy with exceptional strength through traditional hot-extrusion techniques. This alloy exhibits a tensile yield strength of 440 MPa and an acceptable ductility of 4.5%, surpassing a majority of previously reported Mg–Zn-RE-based alloys. Our findings demonstrate that the addition of Gd in Mg–Zn-based alloys effectively retards dynamic recrystallization (DRX) during extrusion, leading to the formation of a distinctive bimodal structure comprising approximately 13.8% coarse un-recrystallized (unDRXed) grains and about 86.2% fine DRXed grains. Furthermore, the alloying effect of Gd enhances particle density, including micron-sized particles and dynamic nano-precipitates. These dynamic precipitates play a crucial role in impeding dislocation movement during extrusion, thereby contributing to the formation of bimodal structure. Additionally, both nano-precipitates and segregation of Zn and Gd atoms towards grain boundaries facilitate the formation of fine DRXed grains through pinning effect. Consequently, the significantly increased tensile yield strength observed in our Gd-modified alloy can be attributed to multiple strengthening mechanisms: fine DRXed grains, strong texture exhibited by unDRXed grains, numerous dynamic precipitates, high-density residual dislocations, and co-segregation of solutes. However, the formation of bimodal structure worsens the yield asymmetry of the Gd-modified alloy due to its strong basal texture. These results provide a valuable insight for further development efforts aimed at achieving ultra-high-strength Mg–Zn-RE-based alloys.

Microstructure characteristics, yield asymmetry and fracture mechanism of the fine grained thin-wall Mg-6.03Zn-0.55Zr tubes fabricated by hot spinning

In this study, thin-wall Mg-6.03Zn-0.55Zr alloy tubes consisted of fine dynamic recrystallized (DRXed) grains and ultrafine grains were successfully obtained by hot spinning process. The results showed that the microstructures of the initial extruded tubes were greatly refined with average grain sizes of 4.46–10.32 µm (300–450 ℃) due to the DRX process, especially at low spinning temperatures. Moreover, the basal texture was transformed from extruded fiber texture to spun tilted plane texture with an angle of ∼10° deviated from the axial direction (AD). More specifically, the basal texture was weakened along AD but was strengthened along the transverse direction (TD) compared with the extruded texture due to the reduced difficulty in pyramidal <c+a> slip activation and the shear deformation induced by the rollers. Consequently, the spun Mg-6.03Zn-0.55Zr alloys showed significant yield asymmetry along AD and TD at room temperature and the increase in spinning temperature had a negative influence on yield strength (YS) that the YS along AD decreased from 290 ± 5 MPa (300 ℃) to 232 ± 2 MPa (450 ℃) and the YS along TD decreased from 236 ± 6 MPa (300 ℃) to 198 ± 4 MPa (450 ℃). Both texture and grain refinement were the important factors in the mechanical properties according to the Hall-Petch relationship due to the varied activation fractions of deformation modes along AD and TD, especially the activation of prismatic <a> slip. Moreover, the fracture mechanism of the spun alloys consisting of fine DRXed grains and ultrafine grains was unusual. The aggregated ultrafine grains played a negative role in the fracture mechanism, because the ultrafine grains were transformed from the dislocation cells and the micro-crack easily occurred in the ultrafine grains.

Achieving low tension-compression yield asymmetry and ultrahigh strength in Mg–1Al–1Ca–0.2Mn (wt%) alloy via sub-micron grain refinement

Traditional low-alloyed Mg–Al–Ca–Mn extrusion alloys always show a low strength and a high tension-compression yield asymmetry. In the present work, Mg–1Al–1Ca–0.2Mn (AXM1102, wt.%) alloys were extruded at 150–350 °C to produce different grain structure and mechanical properties. It is shown that AXM1102-150 (extruded at 150 °C) sample exhibits superhigh strength in both tension and compression, which exhibited a yield strength (YS) of 428 MPa in tension and 416 MPa in compression. Namely, ultrahigh strength and low tension-compression yield asymmetry were both obtained. The ultrahigh strength was found to be ascribed to the ultra-fine dynamically recrystallized (DRXed) grains (0.47 μm) together with grain boundary co-segregation of Ca and Al atoms. Submicron DRXed grains accounts for the improved tension-compression yield asymmetry through suppressing {10-12} twining during compression. Additionally, the discontinuous yielding was detected during tension of AXM1102-150 alloy, which is potentially related with the high energy barrier required for dislocation emission caused by grain boundary co-segregation of Al and Ca atoms. Once the tensile stress reaches the peak value, the mobile dislocation density increases immediately, thus the tensile stress-strain behavior of the AXM1102-150 alloy is dominated by strain softening. The results indicate that low-alloyed Mg–Al–Ca–Mn alloys demonstrate tremendous potential as next generation ultrahigh-strength and low tension-compression yield asymmetry wrought Mg alloys.

Effect of extrusion temperature on the microstructure and mechanical properties of hot-extruded ZK60 magnesium alloy

ZK60 magnesium alloy was prepared by the hot-pressed sintering combined with the hot-extruded technique. The microstructure and mechanical properties evolution of ZK60 alloy with a reduced extrusion temperature from 350 °C to 250 °C were investigated in detailed. The extruded alloy was mainly composed of fine α-Mg grains and MgZn2 phase. The grains size gradually decreased with a reduction in extrusion temperature, and the yield strength obviously increased accordingly. The alloy extruded at 250 °C exhibited the smallest average grain size of 2.5 μm and the best combination of strength and plasticity, with a yield strength of 279 MPa and fracture strain of 18.1% in compressive condition, and 263 MPa and 13.7% in tensile condition, as well as a tension-compression yield asymmetry of 0.94. Both the fine grains formed by the continuous and twin induced dynamic crystallization mechanism and the precipitation strengthening contributed to the strength improvement.

Dislocation-density-related constitutive model and its applicability to cyclic deformation and damage behavior of 316LN SS at 823 K

In the present investigation, an in-depth understanding of the relationship between dislocation kinetics and cyclic plasticity, along with the description of yield asymmetry behavior during loading and unloading in nuclear grade 316LN austenitic stainless steel at 823 K, was examined by employing a constitutive framework using the evolution of physically-based internal-state variables. The formulation encompassed a set of first-order simultaneous differential equations that governed the evolution of dislocation density, mean free path of dislocations, and back stress. These variables were interdependent with the power law which described the kinetics of plastic strain rate. The evolution equations were numerically integrated, and the simulated data were fitted to the experimental data up to stabilized cycle at a temperature of 823 K and total strain amplitudes of ±0.004, ±0.006, ±0.008 and ± 0.010. The predicted cyclic stress response as a function of the cyclic number displayed the continuous cyclic hardening from the first cycle to the initiation of stabilized cycle. Further, good agreement between the predicted and experimental hysteresis loops was found at different cycle numbers. The predicted dislocation density and tensile peak values of back/effective stress increased with cyclic hardening and approached the value of saturation at the stabilized cycle. On the other hand, a rapid decrease in mean free path with cycle number was noticed. An increase in total strain amplitude resulted in a systematic increase in dislocation density, peak stress, back stress and effective stress. At the total strain amplitudes above ±0.006, the predicted higher rates of dislocation accumulation and annihilation, and the faster evolution rate of back stress towards saturation led to the development of stable dislocation substructure configurations with a clear distinction between dislocation high/low dense regions. Furthermore, the applicability of the model was extended by including an empirical relationship between the damage variable and cycle number within the power law, thereby enabling predictions of the cyclic stress-strain response beyond the stabilized cycle.

Twinning Deformation and Yield Asymmetry Improvement of Magnesium Alloys by Free-End Torsion

Twinning Deformation and Yield Asymmetry Improvement of Magnesium Alloys by Free-End Torsion

Improvements in mechanical, corrosion, and biocompatibility properties of Mg–Zr–Sr–Dy alloys via extrusion for biodegradable implant applications

In this study, extrusion was performed on Mg‒Zr‒Sr‒Dy alloys for improving their mechanical, corrosion, and biocompatibility properties. Effects of extrusion and alloying elements on the microstructural characteristics, tensile and compressive strengths, corrosion behavior, and biocompatibility were investigated. The Mg‒Zr‒Sr‒Dy alloys were composed of an α-Mg matrix containing {101¯2} extension twins and secondary phases of intermetallic compounds Mg17Sr2 and Mg2Dy. Evolution of basal and rare earth (RE) textures was observed in the extruded alloys and an increase in Dy content to 2 wt.% resulted in texture randomization and strengthening of the RE component, mainly due to particle-stimulated nucleation and a change from discontinuous dynamic recrystallization to continuous dynamic recrystallization, which also led to an improved tension–compression yield asymmetry of 0.87. Extrusion of the alloys significantly enhanced their tensile and compressive properties due to improved distribution of alloying elements and formation of textures. Corrosion rates tested by hydrogen evolution testing, potentiodynamic polarization, and electrical impedance spectroscopy showed similar trends for each composition, and the lowest corrosion rate of 3.37 mmy−1 was observed for the Mg-1Zr-0.5Sr-1Dy in the potentiodynamic polarization testing. Dy2O3 was observed in the inner layers of the Mg(OH)2 protective films, whose protective efficacy was confirmed by charge-transfer and film resistances. A comparison among the minimum CRs observed in this study and previously studied as-cast Mg‒Zr‒Sr‒Dy and extruded Mg‒Zr‒Sr alloys, demonstrates that both the extrusion process and addition of Dy in Mg‒Zr‒Sr improved the CR. Similarly, extruded Mg–Zr–Sr–Dy alloys showed improved cell viability and adhesion of human osteoblast–like SaOS2 cells due to increased corrosion resistance and enhanced Sr distribution within the Mg matrix.

Towards reducing tension-compression yield and cyclic asymmetry in pure magnesium and magnesium-aluminum alloy with cerium addition

In this study, we report the effect of cerium (Ce) addition on the tension-compression yield and cyclic asymmetry in commercially pure magnesium (Cp-Mg) and Mg–Al alloy at room temperature (RT). The investigated materials Cp-Mg, Mg-0.5Ce, and Mg–3Al-0.5Ce were extruded at 400 °C, followed by annealing at the same temperature for 1 h. Incorporating 0.5 wt% Ce in pure Mg results in the weakening of its basal texture, uniform distribution of Mg12Ce precipitates, and grain size refinement. Consequently, the tensile yield strength and ductility of pure Mg increased, and tension-compression yield asymmetry was eliminated. However, the presence of 3 wt% Al in Mg suppresses the beneficial effects of Ce addition. The formation of non-uniformly distributed complex precipitates, such as Mg–Al–Ce and Al11Ce3, limits the weakening of the basal texture, reduction in grain size, improvement in ductility, and elimination of tension-compression yield asymmetry observed in Mg-0.5Ce. Nevertheless, Al contributes to the solid solution strengthening in Mg and possibly lowers the critical stress required for twinning in Mg, resulting in the highest tensile strength of Mg–3Al-0.5Ce. Finally, the addition of 0.5 wt% Ce enhances the cyclic strength, stabilizes cyclic stress response, reduces inelastic strain, and minimizes cyclic asymmetry in both pure Mg and Mg–Al alloy while maintaining a comparable fatigue life. Overall, Ce addition positively impacts the microstructure and mechanical behavior of pure Mg and its investigated alloy. The reasons for these improvements are discussed in detail.

Effect of Pyramidal Plane II Twinning in Tensile Deformation on Tensile–Compression Yield Asymmetry in Three Orthogonal Directions of Mg Alloy

Effect of Pyramidal Plane II Twinning in Tensile Deformation on Tensile–Compression Yield Asymmetry in Three Orthogonal Directions of Mg Alloy

Exploring the potential of Mg-Zn-Mn-Ca/ZnO composites as a biodegradable alternative for fracture fixation: microstructural, mechanical, and in-vitro biocompatibility analysis

The current research investigates the microstructural, mechanical, in vitro degradation, biocompatibility, and in silico biomechanical behaviour of highly alloyed Mg-Zn-Mn-Ca quaternary system reinforced with ZnO nanopowder as candidate material for resorbable fixation devices. The as-cast composite materials showed dendritic microstructure comprising of α-Mg as major constituent and Mg7Zn3 and Ca2Mg6Zn3 phases distributed in interdendritic zones, as revealed by X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy. The addition of ZnO led to a 17% and 22% increase in ultimate and yield strengths in tension and a 24% and 27% enhancement in ultimate compressive and compressive yield strengths, respectively. The mechanical strengthening and observed tension–compression reversed yield asymmetry strongly correlated with the lattice distortion (c/a ratio) resulting from the macroalloying. The amplitude-dependent internal friction confirmed the presence of immobile obstacles to dislocations and their role through their hysteretic-type anelastic response. The in vitro degradation results revealed corrosion barrier effect of secondary phases. The cell adhesion, viability, and cytoskeleton observations favoured their biocompatibility except for hemolysis rate. The finite element results showed reduced stress-shielded zone for developed materials indicating the favourable mechanical environment for peri-implant tissues at fracture interface required for faster fracture healing.