Low-temperature Extrusion Research Articles

Culinary properties, nutritional quality, and in vitro starch digestibility of innovative gluten-free and climate smart cowpea-based pasta

This study investigates the processability, culinary and rheological properties, biochemical composition and in-vitro starch digestibility of new gluten-free pasta formulated with whole cowpea flour alone or combined with teff and/or amaranth leaf flour(s). These pasta are compared with three wheat-based pasta with fiber content increasing from 4% to 16% g/100g, 16% g/100g being the average fiber content of cowpea-based pasta. The pasta were processed using low temperature extrusion and drying. The antioxidant properties of amaranth leaf flour facilitated extrusion by limiting excessive aggregation of the dough during hydration/mixing that is attributed to lipoxygenase activity of cowpea flour. The optimal cooking time and cooking losses of cowpea-based pasta were similar to wheat-based pasta with comparable fiber content, highlighting fiber as a key factor influencing culinary properties. Adding teff to cowpea-based pasta reduced cooking losses and firmness. Although some micronutrients were lost during pasta processing and cooking, the consumption of a cooked portion of 100 g of dry cowpea-based pasta still covered FAO nutritional recommendations for protein, fiber, iron, zinc, and vitamin B9 targeting adult women. Adding amaranth leaves helped meet recommended beta-carotene levels. The in vitro slowly digestible starch content of cowpea-based pasta is similar to or higher than that of wheat-based pasta.

Optimization of Non-Thermal Treatment Methods and Extrusion Temperature on Quality of Rice Pasta Enriched with <i>Cirina butyrospermi</i>

Food security remains a critical global challenge, necessitating the exploration of sustainable and nutrient-rich food alternatives such as edible insects. This study investigated and optimized the effect of treatment methods (boiling, ultrasound, and a combined boiling and ultrasound treatment) on Cirina butyrospermi and extrusion temperature (70℃, 80℃ and 90℃) on some quality (crude protein, in-vitro protein digestibility, calcium, zinc, iron, cooking time, water uptake ratio, lightness, and colour change) of rice pasta. The effect of treatment methods on Cirina butyrospermi powder and extrusion temperature on crude protein ranged from 15.85 to 18.27%, in-vitro protein digestibility (80.42-88.55%), calcium (48.53-56.25 mg/100g), zinc (2.42-3.56 mg/100g), iron (3.34-5.13 mg/100g), cooking time (8.50 - 19.50 min), water uptake ratio (1.15 - 1.90), lightness value (4.19 - 50.73) and colour change (4.47 - 51.13), respectively. The combined boiling and ultrasound treatment on Cirina butyrospermi powder and higher extrusion temperature gave rice pasta the highest protein, calcium, zinc, and iron content while lower extrusion temperature along with boiling treatment, increased in-vitro protein digestibility. Optimum conditions for desirable rice pasta were achieved at 80°C extrusion temperature with combined boiling and ultrasound treatment. Conclusively, exploring edible insects like Cirina butyrospermi under an accurate treatment method and extrusion condition could aid in the development of nutrient-rich rice pasta.

Gradient high-Content SiC/Al composites via innovative filtration-Extrusion

High-content SiC/Al materials have great potential for thermal management applications in electronic devices owing to their excellent thermal performances. This paper introduces a novel approach to prepare gradient high-content SiC/Al composites using filtration-extrusion technology. The results reveal that the extrusion pressure increases with the filtration-extrusion ratio. In the initial stage, SiC particles are squeezed into the die separation holes, but the distribution range is limited. As the extrusion pressure sharply increases, the distribution range of SiC particles in the separation holes significantly expands, leading to a larger deviation between the actual SiC content and the designed content. A lower extrusion temperature, larger separation hole-to-mold area ratio and higher initial SiC content all contribute to a larger discrepancy. This study provides valuable insights into the filtration-extrusion process, offering a foundation for optimizing the production of high-content SiC/Al composites and enhancing their thermal management applications.

Effects of extrusion temperature on the microstructure and mechanical properties of low-alloyed Mg-Bi-Ca-Mn alloy

A new rare earth-free low-alloyed Mg-0.5Bi-0.8Ca-0.8Mn (wt.%) alloy was prepared at three extrusion temperatures (225, 250 and 275 °C). The effects of low-temperature extrusion on the microstructure and mechanical properties of the alloy were studied. Experimental results show that the dynamic recrystallization (DRX) grains are significantly refined by low-temperature extrusion, and the dynamic recrystallization process is further delayed by the Mn precipitate phase, resulting in a bimodal structure composed of ultrafine DRXed grains and coarse undynamic recrystallized (unDRXed) regions. At an extrusion temperature of 225 °C, the grain size was significantly refined, with an average DRXed grain size of 0.84 μm and a tensile yield strength of 418 MPa. Compared with other extruded magnesium alloys, the ultra-fine DRXed grains, strong basal fiber texture, high Schmid Factors of pyramidal <c + a> slip in the unDRXed regions, and along with a certain amount of second phase (Mg2Ca) distributed along the grain boundaries and nano-Mn particles uniformly distributed in the matrix, are the main reasons for the strength enhancement of low-temperature extruded magnesium alloys. The orientation of the DRXed grains in the alloy after extrusion at 250 °C is more random, which improves ductility. In addition, when the extrusion temperature reaches 275 °C, the alloy shows a fully recrystallized structure and exhibits rare earth (RE)-texture, obtaining high ductility but decreasing strength. This study provides a new idea for the development of high-strength Mg-Bi-based magnesium alloys by adjusting the extrusion temperature and alloying elements. This new high-strength and low-alloyed Mg-Bi-based alloy will help to enrich the series of high-performance, rare-earth free, low-cost extruded Mg alloy with certain application prospects.

Severely weakened extrusion strengthening effect in porthole die extrusion of Al-Mg-Si alloy miniature complex hollow profile under an ultra-large extrusion ratio

Ultra-large extrusion ratio is hardly inevitable during porthole die extrusion of miniature complex hollow profile on industrial horizontal extruders. Although batch extrusion of miniature complex hollow profile has been achieved at ultra-large extrusion ratio, their microstructure and mechanical properties are still unclear. To this end, under the extrusion temperature ranging from 400 ℃ to 480 ℃, a 4×4 mm Al-Mg-Si alloy micro heat pipe profile was extruded at an ultra-large extrusion ratio of 137. The grain size and crystal orientation of the profile were obtained by metallographic and electron backscattered diffraction (EBSD) techniques, and further exploration of the microhardness, tensile properties and pressure-resisting performance were conducted. Interestingly, severely weakened extrusion strengthening effect and low sensitivity of microstructure and mechanical properties to extrusion temperature were observed. Compared to the as-cast extrusion billet, the profile exhibits slight grain refinement and improvement in mechanical performance, and the extrusion temperature does not significantly affect the microstructure and mechanical properties. Instead, as the extrusion temperature increases, the recrystallization fraction generally decreases. These abnormal phenomena are inferred from the fact that even at lower extrusion temperatures, an ultra-large extrusion ratio leads to premature dynamic recrystallization (DRX), and more abnormal growth grains are formed in the profile, weakening the mechanical properties. The higher the extrusion temperature, the earlier DRX occurs, generally forming more abnormal growth and dynamic recovery grains.

Red Potato Pulp and Cherry Pomace for Pasta Enrichment: Health-Promoting Compounds, Physical Properties and Quality

Cherry pomace and red potato pulp were examined as a source of nutritional and health-promoting compounds in pasta products, which could gain popularity among consumers. An attempt was made to obtain such pasta with the help of low-temperature extrusion (50 °C). The purpose of the study was to demonstrate which additive and in what quantity would have a more favorable effect on the nutritional, pro-health and physical quality of pasta. It was found that all pasta samples obtained with cherry pomace had a higher content of fat (10%), ash (3%), fiber (2 times) and polyphenols (22%), together with α tocopherols, than pasta with red potato pulp. Nonetheless, it had a lower water-binding capacity (20%) and higher optimum cooking time. Pasta with cherry pomace was characterized by a good taste and an attractive smell, so this additive should be recommended to obtain products with better nutritional and pro-health value and quality, especially at 30%.

Precision control and parameter optimization in screw extrusion 3D printing of polypropylene materials

Fused Deposition Modeling (FDM), a widely-utilized additive manufacturing (AM) technology, has found significant favor among automotive manufacturers. Polypropylene (PP) compound is extensively employed in the production of automotive parts due to its superior mechanical properties and formability. However, aiming at the problem of poor dimensional accuracy of pure PP parts, the quality of products can be enhanced by optimizing the combination of processing parameters. In this paper, the dimensional accuracy of 3D-printed components made from pure PP material is investigated. Key influencing factors such as infill percentage, infill pattern, layer thickness, and extrusion temperature are considered. To gain a deeper understanding, fluid simulation is conducted, and mathematical models are established to correlate processing parameters with dimensional accuracy. Furthermore, the Taguchi's experiments are designed and the experimental data are subjected to rigorous Signal-to-Noise ratio and ANOVA analyses. Within the experimental range, the lower extrusion temperature, infill percentage and layer thickness yield the best dimensional accuracy. Considering the influence factors of X, Y and Z directions, the optimal processing parameters for PP prints using screw extrusion 3D printers are determined as follows: an extrusion temperature of 210 °C, an infill percentage of 40 %, a layer thickness of 0.3 mm, and a concentric circle infill pattern. This study provides reference value for the subsequent improvement of the dimensional accuracy of the printed parts.

Effect of Cu addition on the thermal conductivity and mechanical properties of Mg–Zn-xCu-Ce alloys

Thermal conductivity and mechanical properties of Mg–Zn-xCu-Ce alloys with different Cu contents under low extrusion temperature were systematically investigated in this work. The results shows that MgZnCu and Ce-rich (Mg, Zn, Cu, Ce) phase were formed in Mg–Zn-xCu-Ce alloys with high Cu content, which have significantly effect on the thermal conductivity and dynamic recrystallization (DRX). The distribution of grain morphology and LAGBs indicates that CDRX is the main mechanism. The addition of Cu element has an inhibitory effect on the DRX behavior, greatly refining the DRXed grains. After extrusion, a large amount of nano-phase is dispersed in the MZEC alloy, which has a strong pinning effect on dislocations. The formation of MgZnCu phase with high thermal conductivity sacrifices the solute atoms of Zn and Cu in α-Mg matrix, which leads to reduction of lattice distortion of Mg matrix, thereby ensuring high thermal conductivity of Mg–Zn–Cu–Ce ternary magnesium alloys. With the increase of Cu content, the strength and thermal conductivity of the alloy gradually increases. When the Cu content is 3.6 wt%, UTS (ultimate tensile strength), YS (yield strength), EL (elongation) and thermal conductivity are 350 MPa, 317 MPa,15.8% and 135 W/m∙K, respectively.

Pivotal role of polylactide in carbon emission reduction: A comprehensive review

AbstractThis review paper explores the diverse applications of polylactide or polylactic acid (PLA) and its contributions to environmental sustainability. It delves into the synthesis, properties, and numerous applications of PLA, accompanied by illustrative examples demonstrating its ability to reduce carbon emissions. The environmentally friendly characteristics of PLA, coupled with its versatility, make it a vital player in the ongoing efforts to combat climate change. PLA generally requires lower extrusion temperatures than other 3D printing materials, such as ABS (Acrylonitrile Butadiene Styrene). Lower extrusion temperatures lead to reduced energy consumption during the printing process thus the reduction in carbon dioxide emissions during production. Plants, such as corn and sugarcane, play a crucial role in absorbing carbon dioxide from the atmosphere during their growth cycle. When these plants are utilized to produce PLA, the captured CO2 remains sequestered within the plastic material. This contributes to offsetting CO2 emissions from other sources. In conclusion, the usage of PLA has demonstrated positive contributions to the reduction of carbon dioxide emissions through its renewable sourcing, lower extrusion temperatures, lower dependence on fossil fuels, reduced greenhouse gas emissions during production, biodegradability, and participation in a closed carbon cycle.

A Novel Low-Temperature Extrusion Method for the Fused Filament Fabrication of Fluoroelastomer Compounds.

In this work, an additive manufacturing process for extruding fully compounded thermosetting elastomers based on fluorine-containing polymer compositions is reported. Additive manufacturing printers are designed with a dry ice container to precool filaments made from curable fluoroelastomer (FKM) and perfluoroelastomer (FFKM) compounds. A support tube guides the stiffened filament towards the printer nozzle. This support tube extends near the inlet to a printer nozzle. This approach allows low-modulus, uncured rubber filaments to be printed without buckling, a phenomenon common when 3D printing low-modulus elastomers via the fused deposition modeling (FDM) process. Modeling studies using thermal analyses data from a Dynamic Mechanical Analyzer (DMA) and a Differential Scanning Calorimeter (DSC) are used to calculate the Young's modulus and buckling force, which helps us to select the appropriate applied pressure and the nozzle size for printing. Using this additive manufacturing (AM) method, the successful printing of FKM and FFKM compounds is demonstrated. This process can be used for the future manufacturing of seals or other parts from fluorine-containing polymers.

Low-Temperature Extrusion of Waterborne Polyurethane-Polycaprolactone Composites for Multi-Material Bioprinting of Engineered Elastic Cartilage.

3D bioprinting of elastic cartilage tissues that are mechanically and structurally comparable to their native counterparts, while exhibiting favorable cellular behavior, is an unmet challenge. A practical solution for this problem is the multi-material bioprinting of thermoplastic polymers and cell-laden hydrogels using multiple nozzles. However, the processing of thermoplastic polymers requires high temperatures, which can damage hydrogel-encapsulated cells. In this study, the authors developed waterborne polyurethane (WPU)-polycaprolactone (PCL) composites to allow multi-material co-printing with cell-laden gelatin methacryloyl (GelMA) hydrogels. These composites can be extruded at low temperatures (50-60 °C) and high speeds, thereby reducing heat/shear damage to the printed hydrogel-capsulated cells. Furthermore, their hydrophilic nature improved the cell behavior in vitro. More importantly, the bioprinted structures exhibited good stiffness and viscoelasticity compared to native elastic cartilage. In summary, this study demonstrated low-temperature multi-material bioprinting of WPU-PCL-based constructs with good mechanical properties, degradation time-frames, and cell viability, showcasing their potential in elastic cartilage bio-fabrication and regeneration to serve broad biomedical applications in the future.

Toward high strength and large strain hardening Zn alloys via a novel multiscale-heterostructure strategy

Zn alloy has attracted much attention as a biodegradable material for biomedical applications. However, due to the significant strain softening of Zn alloys, how to break the bottleneck of synergistic yield strength and uniform elongation is an urgent problem to be solved. In this work, a Zn-2.3Cu-0.8Mn (wt.%) alloy was fabricated via low-temperature extrusion and annealing at 330 °C for 1 h to attain dual heterostructures with bimodal grains and multi-scale second phases, focusing on the effect of heterostructure on the mechanical properties. Uniaxial tensile test and loading-unloading-reloading test were applied to reveal the mechanical properties of the Zn-2.3Cu-0.8Mn alloy, while scanning electron microscope, electron backscatter diffraction, and transmission electron microscope were used to characterize its microstructure. Compared with the as-extruded alloy with uniform and fine grains, 330–1 alloy achieves a better combination of strength and uniform elongation (yield strength: 287.8 ± 8.5 MPa, ultimate tensile strength: 321.4 ± 6.8 MPa, and uniform elongation: 14.2 ± 1.8%). The high strength was primarily attributed to the coordination of grain boundary strengthening, hetero-deformation induced strengthening, Orowan strengthening, and dislocation strengthening. Besides, the coarse grains, twinning, as well as the suppression of grain boundary sliding and phase boundary sliding promoted dislocation proliferation and storage capacity, thereby improving work hardening capacity. The large strain hardening capacity was responsible for excellent plasticity. This study provides a feasible strategy for the design of Zn-based alloys with an excellent combination of high strength and strain hardening capacity.

Preparation of ultrafine-grained Mg–Mn–Ce alloy with high ductility and energy absorption by coupling extrusion and forging

An ultrafine-grained (UFGed) Mg–0.9Mn–0.5Ce (wt.%) alloy with high compressive ductility and energy absorption was developed using a low-temperature deformation method of coupling extrusion and forging. Specifically, the alloy was extruded at 150 °C with an extrusion ratio of 12:1, followed by forging at 200 °C to a true strain of 1.2 along the extrusion direction. The microstructure and plastic mechanism were uncovered using optical microscopy, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. The microstructure was found to consist of ultrafine dynamically recrystallized (DRXed) grains and fragmented unDRXed grains, exhibiting an average grain size of 1.9 μm after low-temperature extrusion. After forging, new UFGs were gradually generated, a uniform UFGed microstructure with an average grain size of 2.7 μm was obtained, and the texture intensity was decreased as well. The homogenous UFGs and basal slip collaboratively contributed to better comprehensive performance of the UFGed alloy, such as a high compressive ductility of 45.0% and a high energy absorption of 122.72 MJ/m3.

Biodegradable Fiber-Reinforced Gluten Biocomposites for Replacement of Fossil-Based Plastics.

Biocomposites based on wheat gluten and reinforced with carbon fibers were produced in line with the strive to replace fossil-based plastics with microplastic-free alternatives with competing mechanical properties. The materials were first extruded/compounded and then successfully injection molded, making the setup adequate for the current industrial processing of composite plastics. Furthermore, the materials were manufactured at very low extrusion and injection temperatures (70 and 140 °C, respectively), saving energy compared to the compounding of commodity plastics. The sole addition of 10 vol % fibers increased yield strength and stiffness by a factor of 2-4 with good adhesion to the protein. The biocomposites were also shown to be biodegradable, lixiviating into innocuous molecules for nature, which is the next step in the development of sustainable bioplastics. The results show that an industrial protein coproduct reinforced with strong fibers can be processed using common plastic processing techniques. The enhanced mechanical performance of the reinforced protein-based matrix herein also contributes to research addressing the production of safe materials with properties matching those of traditional fossil-based plastics.

Optimizing rheological properties for printability: low-temperature extrusion 3D printing of hydroxyapatite-polycaprolactone mixture inks for bone tissue engineering

Introduction: Low-temperature extrusion three-dimensional printing (LTE-3DP) using viscous ceramic-polymer inks has shown promise for bone tissue engineering. This process involves formulating a flowable ink by combining ceramic powders and other components with organic or inorganic polymer solutions, which can then be extruded through a 3D printer nozzle. LTE-3DP allows the incorporation of high fractions of bioactive ceramics and thermally labile additives such as drugs, proteins, and biomolecules into the inks to promote osteogenesis and bone regeneration. The rheology of the ink, influenced by various variables, significantly impacts the printability and form fidelity of the resulting scaffolds. These variables include the composition of the polymer solution and the size and weight ratio of ceramic microparticles. In this study, we posited that the printability of hydroxyapatite (HA) and polycaprolactone (PCL) mixture inks could be optimized by tailoring their rheological properties.Methods: We conducted a systematic investigation, varying the PCL weight percentage and HA:PCL weight ratio, to examine the effects of the ink’s composition on its viscosity and storage modulus, as well as its printability and the mechanical properties of 3D printed HA:PCL scaffolds.Results: We demonstrated that HA:PCL inks exhibit predictable non-Newtonian fluid behavior at higher fractions of HA, displaying significant shear thinning at elevated shear rates, which can facilitate extrusion through a 3D printing nozzle. We identified printable ink compositions based on filament continuity and scaffold form fidelity criteria. Moreover, we performed computational simulations to analyze the ink flow through an extrusion nozzle. These simulations utilized the Herschel-Bulkley-Papanastasiou constitutive model, considering the rheological properties obtained from experimental measurements. By combining experimental measurements and computational simulations, we formulated a non-dimensional Printability number that predicts whether an ink is printable based on the ink’s rheological parameters and printer-specific factors. Furthermore, we evaluated the compressive properties of printed HA:PCL scaffolds and characterized the effects of PCL% and HA:PCL ratio on the hyperelasticity observed in response to compressive deformations.Discussion: This hybrid approach using experimental rheology and FE simulations provides a framework to define the printability of ceramic-polymer ink formulations, which could help streamline the 3D printing of novel inks for bone tissue engineering.

Achieving high strength near 400 MPa in an ultra-fine grained Mg–Bi–Ca ternary alloy via low-temperature extrusion

Significantly enhancing the mechanical properties of Mg–Bi base series alloys is of great significance for their wider application prospects. Here, a new Mg–3Bi–1Ca (BX31, wt.%) alloy showing high tensile yield strength of ∼397.1 MPa, high ultimate tensile strength of ∼416.2 MPa and acceptable elongation of ∼8% was fabricated by low-temperature extrusion. The analysis of microstructure showed that the enhanced yield strength was attributed to the ultra-fine grain structure (∼0.84 μm), nano-scale second phases including Mg2Bi2Ca and Mg2Ca, and Ca segregation at grain boundaries. In addition, a weak basal fiber texture to some extent provided more basal slip activities, guaranteeing the suitable ductility. The dynamic recrystallization and dislocation behavior of the BX31 billet during extrusion were also systematically observed and discussed to reveal the formation mechanisms of the ultra-fine grain structure with the weak basal fiber texture in the as-extruded BX31 alloy. As mentioned above, this work offers a new insight to obtain high-performance Mg–Bi base series alloys.

Effect of extrusion temperatures on the microstructure, texture, and mechanical properties of Mg–5Sn–1Si–0.6Ca alloy

In this paper, the effect of extrusion temperatures (250 °C, 300 °C and 350 °C) on the microstructure, second phases particle, texture, and mechanical properties of the Mg–5Sn–1Si–0.6Ca alloy were discussed. The results show that after extrusion the second phases in the alloy were broken and distributed along the grain boundary. Decreasing the extrusion temperature is beneficial to dynamic precipitation and grain refinement. During the extrusion process, a large number of Mg2Sn nanoprecipitates are dynamically precipitated from the Mg matrix and their number increased and their size decreased with the decrease of extrusion temperature. The grain size was refined from 5.8 μm to 3.328 μm with the extrusion temperature decreasing from 350 °C to 250 °C. Besides, the texture intensity was also reduced with the decrease in extrusion temperature. The strength and plasticity of the Mg–Sn–Si–Ca alloys are simultaneously improved by the method of “solid solution + low-temperature extrusion”. When the extrusion temperature is 250 °C, the alloy obtains superior engineering mechanical properties with the yield strength of 287 MPa, ultimate tensile strength of 343 MPa and elongation to failure of 23.3%. The high strength is mainly attributed to the combined effect of grain size, weak texture, and high density of precipitation. The good ductility is mainly attributed to the grain refinement and high Schmid factors of basal slip.

α-Amylase reactive extrusion enhances the protein digestibility of saponin-free quinoa flour while preserving its total phenolic content

The original cellular structure and the presence of starch are known to reduce quinoa protein digestibility. Here, we aimed at optimizing an integrated single-step process exploiting the synergisms of amylolysis (<0.42% thermostable α-amylase, starch basis) and extrusion (at different temperature profiles) to enhance protein digestibility in saponin-free quinoa flour while minimizing polyphenol losses. In vitro protein digestion rate (velocity of substrate depletion) and extension (percentage of digested substrate at the end of the reaction) were significantly enhanced with every extrusion treatment, reaching up to four-fold faster protein digestion rate and up to 47% reduction of residual non-digested protein at 100 °C (last barrel temperature) and 0.36 g/100 g α-amylase concentration compared to native flour. Generally, reactive extrusion lowered the content of extractable (free) polyphenols and non-extractable proanthocyanins, but this effect was minimized at lower extrusion temperatures and higher α-amylase concentration. Contrarily, the more thermoresistant hydrolysable bound polyphenols increased in all cases, especially at harsh extrusion conditions.

A Study of the Gelatin Low-Temperature Deposition Manufacturing Forming Process Based on Fluid Numerical Simulation.

Low-temperature deposition manufacturing has attracted much attention as a novel printing method, bringing new opportunities and directions for the development of biological 3D printing and complex-shaped food printing. In this article, we investigated the rheological and printing properties of gelatin solution and conducted numerical simulation and experimental research on the low-temperature extrusion process of gelatin solution. The velocity, local shear rate, viscosity, and pressure distribution of the material in the extrusion process were calculated using Comsol software. The effects of the initial temperature, inlet velocity, and print head diameter of the material on the flow field distribution and printing quality were explored. The results show that: (1) the fluidity and mechanical properties of gelatin solution vary with its concentration; (2) the initial temperature of material, inlet velocity, and print head diameter all have varying degrees of influence on the distribution of the flow field; (3) the concentration change of the material mainly affects the pressure distribution in the flow channel; (4) the greater the inlet velocity, the greater the velocity and shear rate in the flow field and the higher the temperature of the material in the outlet section; and (5) the higher the initial temperature of the gel, the lower the viscosity in the flow field. This article is of great reference value for the low-temperature 3D printing of colloidal materials that are difficult to form at room temperature.

Effect of Initial Microstructure Prior to Extrusion on the Microstructure and Mechanical Properties of Extruded AZ80 Alloy with a Low Temperature and a Low Ratio

Magnesium (Mg) alloys are the lightest metal structural material for engineering applications and therefore have a wide market of applications. However, compared to steel and aluminum alloys, Mg alloys have lower mechanical properties, which greatly limits their application. Extrusion is one of the most important processing methods for Mg and its alloys. However, the effect of such a heterogeneous microstructure achieved at low temperatures on the mechanical properties is lacking investigation. In this work, commercial AZ80 alloys with different initial microstructures (as-cast and as-homogenized) were selected and extruded at a low extrusion temperature of 220 °C and a low extrusion ratio of 4. The microstructure and mechanical properties of the two extruded AZ80 alloys were investigated. The results show that homogenized-extruded (HE) sample exhibits higher strength than the cast-extruded (CE) sample, which is mainly attributed to the high number density of fine dynamic precipitates and the high fraction of recrystallized ultrafine grains. Compared to the coarse compounds existing in CE sample, the fine dynamical precipitates of Mg17(Al, Zn)12 form in the HE sample can effectively promote the dynamical recrystallization during extrusion, while they exhibit a similar effect on the size and orientation of the recrystallized grains. These results can facilitate the designing of high-strength wrought magnesium alloys by rational microstructure construction.