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Copyright of Steel Pipe is the property of Steel Pipe Magazine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, the microstructure and mechanical properties of hot-extruded Mg-6Al-2Nd-xCa (x = 0, 1.0, 2.0) alloys were investigated. The experimental results showed that the Mg-6Al-2Nd-xCa (x = 0, 1.0, 2.0) alloys were occurred partial dynamic recrystallization after hot extrusion deformation, and the grain size was refined obviously. Under the action of hot extrusion, the intermetallic phase had fractured and was streamlined along the extrusion direction. The intermetallic phase distribution was more dispersed and uniform than that of the as-cast alloy. At room temperature, 175, 200, 225 and 250 °C, the ultimate tensile strength and yield strength of the hot-extruded alloys increased significantly with increasing Ca content, respectively. The ultimate tensile strength of hot-extruded Mg-6Al-2Nd-xCa (x = 0, 1.0, 2.0) alloys at room temperature and 250 °C was 269.0, 270.8, 289.3 and 66.1, 73.8, 77.8 MPa, respectively. In addition, the hot-extruded Mg-6Al-2Nd-xCa alloys exhibited good plasticity at high temperature deformation. The elongations of hot-extruded Mg-6Al-2Nd-xCa (x = 0, 1.0, 2.0) alloys at 250 °C were 75.0, 72.9 and 69.5%, respectively. [ABSTRACT FROM AUTHOR]

Magnesium alloys are attractive candidates for use as temporary fixation devices in osteosynthesis because they have a density and Young's modulus similar to those of cortical bone. One of the main requirements for biodegradable implants is its substitution by tissues during the healing process. In this article, the Mg–Zn–Ga–(Y) alloys were investigated that potentially can increase the bone growth rate by release of Ga ions during the degradation process. Previously, the effectiveness of Ga ions on bone tissue regeneration has been proved by clinical tests. This work is the first systematic study on the microstructure and mechanical properties of Mg–Zn–Y alloys containing Ga as an additional major alloying element prepared by the hot-extrusion process. The microstructure and phase composition of the Mg–Zn–Ga–(Y) alloys in as-cast, heat-treated, and extruded conditions were analyzed. In addition, it was shown that the use of hot extrusion produces Mg–Zn–Ga–(Y) alloys with favorable mechanical properties. The tensile yield strength, ultimate tensile strength, and elongation at fracture of the MgZn4Ga4 alloy extruded at 150 °C were 256 MPa, 343 MPa, and 14.2%, respectively. Overall, MgZn4Ga4 alloy is a perspective for applications in implants for osteosynthesis with improved bone regeneration ability. [ABSTRACT FROM AUTHOR]

The black soldier fly (Hermetia illucens L.) is a potential substitute of fish meal in feeds. However, information on the nutrition and safety of these feeds is inadequate. This study examined the quality of fish feed pellets extruded from blends formulated with and without black soldier fly larval meal (BSFLM). A further aim was to study the influence of extrusion processing types on feed composition. Two iso-proteinous feed blends containing 28% protein were formulated with 0% BSFLM (BSFLM0) and 75% BSFLM (BSFLM75). The feed blends were then cold- or hot-extruded (CE or HE) and the products analyzed for proximate composition, amino acids, fatty acid profiles and microbial content. The BSFLM75_HE pellets contained significantly higher levels of fat (15.6%), leucine (11.5 mg/g), and oleic acid (79.1 µg/g). Hot extrusion concentrated phenylalanine and leucine, increased polyunsaturated fatty acids and saturated fatty acids and decreased total viable counts, coliforms, yeast and molds, endospores and Salmonella. [ABSTRACT FROM AUTHOR]

The AZ61Mg‒18%Ti (mass fraction) composites were prepared by mechanical milling, vacuum hot pressing, and hot extrusion. The microstructure, room-temperature mechanical properties, and the corresponding strengthening mechanism were studied. The results show that, the average grain size of the magnesium matrix is about 180 nm, the Ti particles and the nano-sized Ti3Al phases are dispersive distribution in the magnesium matrix, and the average grain sizes of Ti particles and Ti3Al phases are 265 nm and 10 nm, respectively. The ultrafine-grained AZ61Mg‒18%Ti composites show the excellent room-temperature mechanical properties, the room-temperature yield strength, the compressive strength, and the fracture strain are 606 MPa, 698 MPa, and 12%, respectively.

In the present study, a new biodegradable Mg-Zn-Cu magnesium alloy was introduced for biological applications. The microstructural analysis showed the formation of MgZnCu intermetallics for the Mg-2Zn-0.1Cu alloy and also the Mg(Zn,Cu)2 compounds for the Mg-2 Zn alloys with higher Cu contents. Moreover, the hot extrusion was applied for the grain refinement and changing the distribution of intermetallics. In vitro immersion tests, electrochemical and corroded surface analyses represented the enhancement of corrosion resistance with 0.1 wt.% Cu addition. Furthermore, the extruded alloys demonstrated more corrosion resistance behavior than that of the cast alloys. By considering the improved tensile properties of Mg-2Zn-0.1Cu alloy, this alloy was regarded as the potential candidate for use as the biodegradable magnesium implant.

Deep traps at grain boundaries, or within grains, of polycrystalline alloys optimized for large-scale thermoelectric applications affect their transport properties. For an accurate description of these properties, defects require appropriate statistical treatment at the basic level, so that the chemical potential can be obtained as a function of temperature. This work reports on polycrystalline p- and n-type bulk hot-extruded ternary alloys and composites containing Bi, Sb, Te and Se which have advantageous mechanical properties and thermoelectric performance below 500 K. Calculations of the electrical transport properties of heavily doped ternary alloys taking into account their polycrystalline nature provide excellent accord to Hall effect transport measurements in the plane perpendicular to the extrusion axis in the range from 10 K to 440 K. To do so, a statistical treatment of deep donor traps at grain boundaries in p-type composites is required. Ignoring their role may lead to incorrect interpretation of transport measurements. [ABSTRACT FROM AUTHOR]

The microstructures and mechanical properties of a hot extruded Al–Zn–Mg–Cu alloy pipe with variable cross-section are investigated by transmission electron microscopy, electron backscattering diffraction, hardness testing and finite element method. The results suggest that the variable temperature distribution at different positions along the extrusion direction after hot extrusion attribute to the changes in hot deformation degrees. The extruded profile at billet temperature of 410 °C and a ram speed of 1.5 mm/s shows a gradual increase in temperature from 416 to 467 °C at strains from 3.7 to 8.6 along the extrusion direction. The dynamic recovery (DRV) and partial dynamic recrystallization (DRX) are observed in the hot extruded profile, and high-angle grain boundaries fraction exponentially rises along the extrusion direction. The hardness at different positions of the hot extruded profile shows a nearly exponential decline along the extrusion direction, mainly ascribes to the decrease of the dislocation density that caused by the dynamic softening. [ABSTRACT FROM AUTHOR]

Metal matrix nanocomposites are attracting attention because of their great potential for improved mechanical properties and possible functionalization. These hybrid materials are often produced by casting processes, but they can also develop their property profile after hot working, e.g., by forging or extrusion. In this study, a commercial cast magnesium alloy AM60 was enriched with 1 wt.% AlN nanoparticles and extruded into round bars with varied extrusion rates. The same process was carried out with unreinforced AM60 in order to determine the influences of the AlN nanoparticles in direct comparison. The influence of extrusion speed on the recrystallization behavior as well the effect of nanoparticles on the microstructure evolution and the particle-related strengthening are discussed and assessed with respect to the resulting mechanical performance. [ABSTRACT FROM AUTHOR]

Compared to the recycling process by remelting, hot extrusion significantly reduces the energy consumption and CO2 emission and ensures good mechanical and microstructural properties. This study investigates the effects of reinforcing aluminium AA6061 chips with mixed boron carbide (B4C) and zirconia (ZrO2) particles by employing a design of experiment (DOE) under 550 °C processing temperature and three hours preheating time. The findings showed that compressive strength (CS) and hardness increased with up to 5% added particles, and beyond 5%, the yielded values decreased because of materials agglomeration. However, the decreasing density was dependent on the addition of ZrO2 particles. The distribution of particles with different volume fractions of mixed particles was investigated by employing SEM, AFM, and EDS tests. Thus, the process can produce a net shape structure that utilises material-bonding consolidation to provide sufficient support to reuse the recovered materials in engineering applications, such as in the automotive industry. [ABSTRACT FROM AUTHOR]

(AlFeNiCrCoTi0.5)p/6061Al matrix composites were prepared by cold isostatic pressing combined with equal-diameter angular extrusion. The microstructure and properties of the extruded materials after adding high-entropy alloys were studied. The FCC + BCC dual-phase high-entropy alloy particles mechanically alloyed for 90 h were added to the aluminum matrix, while the composite material formed a diffusion interface after equal-diameter angular extrusion. Compared with the 6061Al matrix, when the content of AlFeNiCrCoTi0.5 was 10%, by two passes, the hardness increased from 52.5 HV to 70.3 HV, the tensile strength increased from 158 MPa to 188 MPa, and the elongation changed from 14.9% to 14.1%. The material had good comprehensive mechanical properties. [ABSTRACT FROM AUTHOR]

Copyright of Steel Pipe is the property of Steel Pipe Magazine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A 0.5 wt.% graphene nanoplatelet-reinforced aluminum composite (0.5 wt.% GNPs/Al composite) was prepared by powder metallurgy and extruded at ratios of 8:1, 11:1, 17:1, 25:1 and 36:1 to study the effects of the extrusion ratio on the mechanical properties and microstructure of the composite. It is found that the composite shows the best general mechanical properties at an extrusion ratio of 17:1 tensile strength of 164.49 MPa, elongation of 21.81%, bending strength of 325.47 MPa, and a Young's modulus of 62.01 GPa. An extrusion ratio (8:1 or 11:1) that is too low results in poor grain refinement, separation of the GNP layers and ordinary properties. However, an extrusion ratio that is too large can also lead to grain growth (such as 25:1) or a reduction in GNP integrity (such as 36:1), which affects the strengthening efficiency of hot extrusion negatively. [ABSTRACT FROM AUTHOR]

The microstructure and tensile properties of hot-extruded Al-8Zn-2Mg-2Cu-0.15Zr alloy (7055 alloy) with the minor addition of Sc were investigated. The 0.1 and 0.2 wt.% Sc were added into 7055 alloy during the preparation process by conventional casting. Attributing to the Sc additions, the grain sizes of as-cast ingots were remarkably refined and the irregular grain morphology changed to nearly spherical. Correspondingly, the distinctly refined microstructure of the 7055 alloy with Sc addition was achieved after hot extrusion. Unlike most reported extrusion cases of 7055 alloy, the extrusion temperature and ram speed were set to be 500 °C and 0.1 mm/s, respectively. As the added Sc increased from 0 to 0.1 and 0.2 wt.%, the yield strength (YS) of the T6 treated samples of extruded 7055 alloys were improved from 652 to 660 and 695 MPa, and the ultimate tensile strength (UTS) was 701, 706, and 744 MPa, respectively. The elongation of all the T6 samples remained to be about 11.5%. The good tensile properties of these experimental alloys are mainly attributed to grain refinement, extrusion texture, and the abundant precipitated particles, including Al3(ScZr) and η(MgZn2), which effectively pin the dislocation and hinder the migration of grain boundaries. [ABSTRACT FROM AUTHOR]

Digestibility and retrogradation properties of starch are important for the nutrition and quality of starch-based foods. In this study, a new idea on the synchronous delay the starch digestion and retrogradation was proposed, and the regulation mechanism was explored from perspectives of structural evolution using 13C NMR, XRD and SAXS techniques as well as the molecular dynamics simulations. Results showed that the chestnut starch treated with hot extrusion and 8% catechins (HE-8% CA)## could reach highest anti-retrogradation rate (AR 76.63%) and lowest rapidly digestible starch content (RDS 64.55%) at day 24. The starch digestion was slowed down by increasing single/double helix, V-type crystallinity and compactness of aggregates, while retrogradation process was suppressed by inhibiting the packing of short-range ordered structure into long-range ordered structure. The hydrogen bonding and van der Waals forces were the main driving force for the interactions between flavonoid polyphenols and starch molecules. Overall, this study is instructive for further investigations on the synchronous modulation of functional properties of starch. • The digestion and retrogradation of CS were synchronously slowed down. • The formation of crystalline structure was inhibited during retrogradation process. • The non-covalent interaction with flavonoid polyphenols promoted the formation of short-range ordered structure of CS. • The catechins had a better slowing effect due to the smaller molecular structure. • The correlation and regulation mechanism were further revealed. [ABSTRACT FROM AUTHOR]

Nanomaterials play an important role in metal matrix composites (MMC). In this study, 3.0 wt.%, 6.0 wt.%, and 9.0 wt.% nano-AlN-particles-reinforced AA6061 (nano-AlN/AA6061) composites were successfully prepared by pressure infiltration technique and then hot extruded (HE) at 500 °C. The microstructural characterization of the composites after HE show that the grain structure of the Al matrix is significantly refined, varying from 2 to 20 μm down to 1 to 3 μm. Nano-AlN particles in the composites are agglomerated around the matrix, and the distribution of nano-AlN is improved after HE. The interface between AA6061 and nano-AlN is clean and smooth, without interface reaction products. The 3.0 wt.% nano-AlN/AA6061 composite shows an uppermost yield and supreme tensile strength of 333 MPa and 445 MPa, respectively. The results show that the deformation procedure of the composite is beneficial to the further dispersion of nano-AlN particles and improves the strength of nano-AlN/AA6061 composite. At the same time, the strengthening mechanism active in the composites was discussed. [ABSTRACT FROM AUTHOR]

The dry sliding wear behavior of A7075 based composites strengthened with particulates of ZrB2 was examined using the pin-on-disc device. The composites were synthesized by reinforcing different weight % (5, 10, and 15) of the ZrB2 using a stir casting technique followed by hot extrusion. The dry sliding wear resistance is optimized under varying conditions of sliding velocity, sliding time, and load. The sample's worn-out surfaces were examined using scanning electron micrographs to obtain the composites' wear mechanism. Delamination, abrasion adhesive modes of deformation were observed. The wear parameters were optimized with Grey relational analysis (G.R.A.) and ANOVA techniques and obtained the optimal combination of input parameters.

This study aims to improve the mechanical properties of a Ti–2Fe base alloy by adding W solute and performing hot extrusion at a high temperature (1000 °C). W was added at 0, 1, 2, and 3 wt% using the powder metallurgy route and homogenization heat treatment. The as-extruded materials predominantly consisted of α phase with different microstructure morphologies; Ti–2Fe and Ti–2Fe–1W contained equiaxed α grains, while Ti–2Fe–2W and Ti–2Fe–3W showed equiaxed + acicular and acicular shape, respectively. Effective grain refinement was obtained in Ti–2Fe–2W (average grain size: ~1.64 μm), which greatly contributed to the strengthening. The solid solution of W was studied with X-ray powder diffraction, where a proportional increment of β lattice constant occurred as the W solute increased in the matrix (Ti–Fe). Additionally, electron backscatter diffraction analysis revealed that the W solution reduced the intensity of the prismatic texture along the extrusion direction. Based on the experimental evaluations, extruded Ti–2Fe–2W alloy exhibited a maximum yield strength of 925 MPa with excellent elongation 30% at room temperature, indicating a remarkable trade-off in strength and ductility.

Characteristic of the samples based on Al-Si alloys, that we have studied, is their propensity for oxidation at high temperatures. The few number of papers on the oxidation kinetics of aluminium alloys associated with Planar Flow Casting technology (PFC) can be found in the literature. The oxide processes and the properties of the oxide layer formed on the aluminium alloy are mainly considered. The aim of the present work is the kinetics of oxide layer formation on aluminium alloys to clarify whether alloys are suitable for use in space and under specific conditions. The formal kinetics of Nikitin was applied for data processing. The influence of the alloying elements on the formed surface oxide coating is shown.

Biodegradable Mg-based implants are widely used in clinical applications because they exhibit mechanical properties comparable to those of human bone and require no revision surgery for their removal. Among Mg-based alloys, Mg–Zn–Ca–(Mn) alloys have been extensively investigated for medical applications because the constituent elements of these alloys, Mg, Zn, Ca, and Mn, are present in human tissues as nutrient elements. In this study, we investigated the effect of the hot extrusion temperature on the microstructure, mechanical properties, and biodegradation rate of Mg–Zn–Ca–(Mn) alloys. The results showed that the addition of Mn and a decrease in the extrusion temperature resulted in grain refinement followed by an increase in the strength and a decrease in the elongation at fracture of the alloys. The alloys showed different mechanical properties along the directions parallel and perpendicular to the extrusion direction. The corrosion test of the alloys in the Hanks’ solution revealed that the addition of Mn significantly reduced the corrosion rate of the alloys. The Mg–2 wt% Zn–0.7 wt% Ca–1 wt% Mn alloy hot-extruded at 300 °C with an ultimate tensile strength of 278 MPa, an yield strength of 229 MPa, an elongation at fracture of 10%, and a corrosion rate of 0.3 mm/year was found to be suitable for orthopedic implants.

Considering the high strength of titanium matrix composites (TMCs) at room and elevated temperatures, the aim of this study was to develop novel TMC Ti-4Fe-3W/2TiC (wt%) utilizing powder metallurgy and subsequent extrusion at different temperatures: the two-phase (α+β) and pure β phase regions. The TiC particle dispersion was almost identical in both composites with variation in the size distribution. However, there was a significant difference in the morphology of the α phase in the matrix. The α+β-extruded composite exhibited globular αp (grain size: 0.7 μm); in contrast, the β-extruded phase showed acicular αs (grain size: 1.5 μm). Additionally, α-Ti was the predominant phase in contact with TiC particles due to the semi-coherent relationship between these two phases. A remarkably high yield strength (1215 MPa) was achieved at room temperature in the α+β -extruded composite, while the β-extruded composite exhibited consistently improved strength at high temperatures. Morphological characterization using atomic force microscopy (AFM) revealed the β phase was slightly harder than the α phase, probably due to the solid solution of Fe and W that predominant in the β phase.

In this paper, an axle sleeve is formed through a combined cross wedge rolling (CWR) and hot extrusion process, and the combined forming process is simulated via finite element analysis software Deform-3D. The forming mechanism is revealed by analyzing the stress and strain distribution, the temperature variation and the metal flow law of the workpiece during CWR and hot extrusion. Combined with CWR and hot extrusion forming experiments, the feasibility of a combined rolling and extrusion process to produce an axle sleeve is verified. It has been proven that the outer steps of the axle sleeve produced through the rolling extrusion composite process are well formed, the flange extrusion cavity is full, the metal streamline is continuous, the axis of the inner hole does not easily deviate, the product quality is good and the production efficiency is high.

[Display omitted] • Effective dispersion and good structural integrity for high-content GNS resulted from the hybridization of SiCnp. • The (SiCnp + GNS)/Al composites exhibited refined nanograins and intra-crystalline nanoparticle distribution. • Significantly improved work-hardening capacity was attributed to SiCnp-induced lattice distortion. • Simultaneous enhanced strength and toughness of GNS/Al composite was achieved by hybrid effect with SiCnp and GNS. Good strength-ductility balance in graphene nanosheet (GNS)-reinforced aluminum nanocomposites can be achieved through tailorable and facile agglomeration control. Our previous study showed that pre-modulating the Al powder morphology by adding hard silicon carbide nanoparticles (SiCnp) during the two-step ball milling process effectively promotes the uniform dispersion of GNSs. However, excess SiCnp content causes SiCnp aggregate and premature cracking of composites. Here, GNS-reinforced aluminum nanocomposites with different SiCnp content (0.3–1.5 vol%) were prepared, and the optimal SiCnp-to-GNS ratio was determined after optimizing the SiCnp content in a pre-studied composite preparation process. The effect of SiCnp on the microstructure and mechanical properties of the composites was systematically investigated. The cold welding deformation of Al flakes increased with the SiCnp content. Nonetheless, inadequate or excessive SiC content caused insufficient lamination or excessive cold-weld stacking of Al flakes, respectively. Al-0.9vol.%SiCnp powders possessed the highest specific surface area which resulted in high homogeneous dispersion of 3.0 vol% GNS during the second ball-milling stage. Consequently, the resulting hybrid reinforced (GNS + SiCnp)/Al composites showed simultaneous improvement in strength and plasticity, unlike Al-3.0vol.%GNS composites. This showed that introducing hard nanoparticles (i.e., the hybridization strategy) is a promising method to simultaneously enhance strength and plasticity of aluminum nanocomposites. [ABSTRACT FROM AUTHOR]

Aluminum-matrix composites (AMCs) reinforced with submicron-sized ceramic particles of Al2O3, TiB2 and TiC were in-situ synthesized by reactive sintering of Al, TiO2, and B4C powder mixtures and further densified by hot-extrusion process. The reaction mechanisms for formation of the reinforcing particles, extrusion behavior, microstructure, and tensile properties of the AMCs have been investigated. The reactions of TiO2 and B4C with molten Al were a stepwise process, and there were many intermediate phases including oxygen deficient titanium oxides (Ti3O5, Ti2O3, and TiO), Al4C3, AlB2, and Al3Ti, before the expected reinforcing particles of Al2O3, TiB2, and TiC were formed. The results showed that hot-extrusion process was an effective means to densify reactive-sintered porous composites, and dense AMCs can be obtained through hot-extrusion in a temperature range of 480–550°C. The microstructure of the resulting AMCs was characterized by fine reinforcing ceramic phases with an average particle size of 0.24 μm, which were homogeneously distributed in Al matrix. Furthermore, no significant change in particle sizes could be found after extrusion, and ceramic particle content and extrusion temperature have small influences on the average particle sizes of the reinforcing phases. The presence of these sub-micron hybrid ceramic particles resulted in significant enhancements in yield and tensile strength of the AMCs. The yield strength improvement is mostly due to the coefficient of thermal expansion (CTE) mismatch between the ceramic particles and Al matrix, followed by Orowan strengthening, while the relative contributions of grain refinement and load-bearing effects are much smaller. [ABSTRACT FROM AUTHOR]

In this study, the Al-BN nanocomposite powders were prepared using two different methods of i) ultrasonic mixing, and ii) planetary ball milling. The Al-BN bulk nanocomposite samples were fabricated by hot extrusion. Morphology of powders through the preparation process and fracture surface were characterized using scanning electron microscopy and the microstructure of optimized bulk nanocomposite sample was investigated by a transmission electron microscopy and electron back scattered diffraction technique (EBSD). The mechanical properties of composite samples were examined by uniaxial tension test. With the use of planetary high energy ball milling and hot extrusion, the ultimate tensile strength of fabricated unmilled and milled pure Al samples reached to 104 MPa and 212 MPa, respectively. The ultimate tensile strength of extruded milled nanocomposite increased to 297, 330, 333MPa by adding 1, 2 and 4 wt.% BN, respectively. In the process of composite powders mixing and hot extrusion, the mechanical properties of samples were significantly decreased. By increasing the BN content within range of 0-6 wt.%, the tensile strength of mixing and extruded composite samples was not changed. On the other hand, the ductility is reduced from 24 % for pure Al to 5 % for Al-6 wt.% BN. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and biodegradability. However, in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer from a rapid corrosion rate and severe localized corrosion, which is limiting their widespread application. To solve the problem of uneven degradation of stents, a HTHE (long-time and high-temperature heat treatment, large-reduction-ratio hot extrusion) process is used to manufacture Mg-Zn-Y-Nd alloy microtubes in this study. The heat treatment is to dissolve alloying elements and reduce the size of SPPs, and the hot extrusion is to acquire fine-grained and strongly textured microtubes. The microstructural characterization shows that coarse second phases in as-cast alloy are refined and uniformly distributed in matrix of microtubes. After hot extrusion, microtubes show strong texture with basal plain oriented parallel to the longitudinal section (LS). The corrosion testing indicates that severe localized corrosion occurs on the cross section (CS) while localized corrosion is alleviated on the LS. Based on the different corrosion properties of the LS and CS, HTHEed microtubes are promising for solving the problems of rapid corrosion rate and severe localized corrosion of Mg alloy stents. [ABSTRACT FROM AUTHOR]

The effects of cerium-based rare earth (RE) addition and hot deformation via extrusion on the microstructure and mechanical properties of Mg-0.5Zn-0.5Zr alloy were studied. It was found that RE addition could effectively refine the as-cast microstructure up to 2 wt% RE with a notable grain refining effect up to 1 wt% RE. High RE additions resulted in a less effective grain refinement and the appearance of coarse dendritic microstructure. While the as-cast strength and ductility were enhanced by increasing RE content up to 1 wt% due to grain refinement, alloys with high RE content faced a remarkable drop in total elongation and also showed lower ultimate tensile strength (UTS) values, which was related to the interconnected intergranular brittle intermetallics (Mg12RE) with high volume fractions. For the extruded alloy with 1 wt% RE, besides the fragmentation and dispersion of intermetallics, a remarkable grain refinement due to the recrystallization processes was observed. Accordingly, the UTS of 415 MPa, total elongation of 17% and tensile toughness of 65.9 MJ/m3 were obtained after extrusion, which are quite superior to the corresponding values of 210 MPa, 12% and 22.1 MJ/m3 for the as-cast counterpart, respectively. Regardless of the processing condition, the grain size effect was found to be the dominant factor in determining the yield stress (Hall–Petch law), where the deviation of this trend due to the presence of hard Mg12RE phase was discussed. [ABSTRACT FROM AUTHOR]

To enhance the mechanical properties and poor corrosion resistance of magnesium alloy in vitro, the as‐cast Mg–2Zn–0.5Zr–1.5Dy (mass%) magnesium alloy was subjected to two types of extrusion treatment, one is hot extrusion (denoted as ET alloy), the other is heat treatment followed by hot extrusion (denoted as HE alloy). The microstructure, mechanical properties, and corrosion behaviors of these extruded alloys are assessed. The results show that the HE alloy has superior mechanical properties and a slower corrosion rate than the ET alloy. The yield strength and elongation of the HE alloy reach 287 ± 10 MPa and 17.6 ± 0.5%, respectively, and its corrosion rate is only 0.59 ± 0.16 mm year−1. After hot extrusion, microscale and nanoscale second‐phase exist in the extruded alloys, and the nanoscale second‐phase can improve their mechanical properties by second‐phase strengthening. However, the presence of microscale second phase can cause galvanic corrosion and result in poor corrosion resistance. The HE alloy has good properties due to it containing more nanoscale second‐phase and fewer microscale second‐phase. [ABSTRACT FROM AUTHOR]

The effect of hot extrusion on the corrosion behavior of AZ91 alloy was studied by observing the change of grain size, the size and distribution of precipitated phase on the transverse and longitudinal sections before and after extrusion. The results show that the grain refinement of alloy was significant after extrusion, the grain size of the transverse section was uniform, that of the longitudinal section was different and the parallel streamline of shear stripes appeared. After extrusion, the decrease of the β-Mg17Al12 phase size reduces the relative potential difference between the second phase and the α-Mg matrix; the reduction of the transverse section was particularly significant. Grain refinement and precipitate size reduction after extrusion can improve the corrosion resistance of the AZ91 Mg alloy, which is the reason why the corrosion resistance of the transverse section was better than that of the longitudinal section. [ABSTRACT FROM AUTHOR]

The microstructure evolution of sintered and extruded samples of Al–4Si–0.6Mg powder alloys at various semi-solid temperature ranges of 560 °C, 580 °C, and 600 °C, holding times of 600, 1200, and 1800 s, and strain rates of 0.1, 0.2, and 0.3 s−1 was studied. From the stress–strain curves and metallographic studies, Arrhenius grain growth model and Avrami dynamic recrystallization model have been formulated by means of linear regression. Parameters such as peak strain, critical strain, recrystallization fraction, and material constants have been found using the above equations. The experimental and calculated values of various material parameters agree with each other, indicating the accuracy of the developed model. Finite element method-based simulations were performed using DEFORM 2D software, and the average grain size obtained from experiments and simulations was validated by means of average grain size. The relative density of the compacted specimens as well as the extruded specimens was also simulated. The simulation results showed that large grains appeared at high temperatures and at the bottom of the specimen. [ABSTRACT FROM AUTHOR]

In this paper, the Conditional Average Estimator artificial neural network (CAE ANN) was used to analyze the influence of chemical composition in conjunction with selected process parameters on the yield strength and elongation of an extruded 6082 aluminum alloy (AA6082) profile. Analysis focused on the optimization of mechanical properties as a function of casting temperature, casting speed, addition rate of alloy wire, ram speed, extrusion ratio, and number of extrusion strands on one side, and different contents of chemical elements, i.e., Si, Mn, Mg, and Fe, on the other side. The obtained results revealed very complex non-linear relationships between all of these parameters. Using the proposed approach, it was possible to identify the combinations of chemical composition and process parameters as well as their values for a simultaneous increase of yield strength and elongation of extruded profiles. These results are a contribution of the presented study in comparison with published research results of similar studies in this field. Application of the proposed approach, either in the research and/or in industrial aluminum production, suggests a further increase in the relevant mechanical properties. [ABSTRACT FROM AUTHOR]

The structure, hardness, tensile and wear behavior of Mg–5Sb–xSiC hybrid composites experimented where the amount of SiC particles were 1, 3, and 5 wt% SiCp before and after applying hot extrusion process. Micron size SiC particles were added to Mg–5Sb alloy via stir casting technique to form both Mg3Sb2 and SiC particles in the as-cast microstructures. Although SiC addition reduced the grain size of the Mg–5%Sb in-situ metal matrix composite (MMC), no improvement was observed on ultimate tensile strength (UTS) and the ductility (EL.%) in the as-cast state. The use of the extrusion process led to a remarkable fracturing of Mg3Sb2 intermetallic along the extrusion direction, grain refinement, and reduction in the size of SiC clusters. The optimal amount of SiC was found to be 3 wt%, which reduced the grain size from ~ 827 to ~ 4 µm and promoted the UTS amounts from 120 to 244 MPa for as-cast and hot extruded composites. Besides, the enhancement of yield strength of extruded MMCs was rationalized depending on the grain size compared to the as-cast condition. The fractography of the as-cast composites revealed more cleavage planes in contrast with hot extruded composites, which proved much more dimples. It was also found that the use of hard SiC particles in hybrid composite improved wear properties just in the extruded state. According to observations, in various sliding test conditions, the abrasive, oxidation and delamination are mostly operated in combination. [ABSTRACT FROM AUTHOR]

A novel hot extrusion method to fabricate anisotropic nanocrystalline SmCo5 magnet was investigated. The results indicate that the hot-extruded (HE) SmCo5 magnet obtains a strong $c$ -axis texture in perpendicular to the extrusion direction, but the texture strength is clearly different in different regions. The deformation degree plays a key role in the formation of $c$ -axis crystallographic texture and magnetic anisotropy. In surface region of the HE magnet, the deformation degree of grains is the biggest, and the $c$ -axis texture and remanence are the strongest. Furthermore, deformation mechanism of the HE SmCo5 magnet was preliminarily discussed. [ABSTRACT FROM AUTHOR]

Results are presented for industrial experiments on lead brass extrusion through a two-channel die with process temperature variation. Mechanical properties of the extruded products are measured. Results of processing show that the dependence of ultimate strength on extrusion temperature is extreme in value. A function minimum is observed close to 720°C, and this temperature corresponds to the phase transition point. It is also revealed that leading part of the bar has lower strength than the rear part. Metallographic studies are performed showing differences in grain sizes and phase ratios with variation in temperature and sampling locations. [ABSTRACT FROM AUTHOR]

In the present paper, the effect of initial microstructure on the hot extruded Mg-6Nd-2Al alloy was carried out by microstructural observation and mechanical property testing. The results show that there are short rod-shaped Al11Nd3 phase, strip-shaped Mg12Nd phase and granular Al2Nd phase in the as-cast Mg-6Nd-2Al alloy after hot extrusion. The as-cast alloy is treated by solid solution and then hot extrusion, the granular Al2Nd phase can still be observed in the alloy, and the needle-shaped Al2Nd phase precipitates inside the α-Mg matrix. A typical (0001) texture and {01-10} prismatic surface texture appear in the as-cast alloy after hot extrusion, while in the solid-solution alloy after hot extrusion does not form an obvious preferred orientation. The ultimate tensile strength and the yield strength of the as-cast alloy after hot extrusion are higher, which are 271.2MPa and 247.8MPa, respectively. However, the elongation of the as-cast alloy after hot extrusion is lower, which is 15.3%. [ABSTRACT FROM AUTHOR]

With excellent radiation resistance and high temperature strength, the oxide dispersion strengthened (ODS) nickel-based superalloys are deemed as candidate materials for advanced fission and fusion reactor. Since conventional manufacturing processes are difficult to produce components with complex shapes, additive manufacturing becomes an alternative method. In this work, ODS nickel-based superalloy was manufactured by laser metal deposition (LMD) technology using mechanically alloyed powder. The microstructure and high temperature mechanical properties of the as-deposited alloy were analysed. The results indicated that the as-deposited alloys prepared by this method owned anisotropic structure and uniformly distributed high-density oxides, contributing to superior high-temperature performance, in comparison with the samples produced by LMD using pre-alloyed powder and traditional hot extrusion.

A ternary alloy strengthened by the phase with long period stacking ordered (LPSO) structure with composition of Mg97.5Gd1.9Zn0.6 (atom fraction/%) was prepared by conventional permanent mold casting. The microstructure evolution and mechanical properties in as-cast, as-annealed, as-extruded and extruded-T5 alloy were systematically investigated by OM,SEM,TEM and electronic universal testing machine. The results show that the as-cast microstructure of the alloy consists of the α-Mg matrix, (Mg,Zn)3Gd eutectic and lamellar 14H-LPSO phase. Annealing at 510℃ results in the transformation of (Mg,Zn)3Gd into the block-shaped 14H-LPSO phase. According to the distribution and morphology of the 14H-LPSO phase observed in the microstructure after annealing, the peritectoid transformation (Mg,Zn)3Gd +α-Mg→14H-LPSO possibly occurs during annealing. The lamellar 14H-LPSO and β' p precipitates have also been observed in the alloy during extruded-T5 treatment. Under the combined action of 14H-LPSO toughening and precipitation strengthening, the aged sample shows the best tensile properties at room temperature:ultimate tensile strength of 361 MPa, yield strength of 216 MPa and elongation of 6.9%.

The hot deformation behavior of Mg-6Gd-5Y-0.3Zr alloy at the temperatures of 673–748 K and the strain rates of 0.01–1.0 s−1 were investigated by hot compression experiments. On this basis, a physically based internal state variable (ISV) model coupling the microstructural evolution was established, in which the ISVs of the model included dislocation density, grain size and volume fraction of dynamic recrystallization (DRX). Besides, the recrystallized and un-recrystallized grain sizes were considered to characterize the evolution process of microstructure. By comparing the calculated and experimental flow stresses, the model was proved to be reliable. Then the model was imported into the finite element analysis (FEA) software ABAQUS to predict the ISV evolution of Mg-6Gd-5Y-0.3Zr alloy in the hot extrusion process. The comparative analysis of the simulation and experimental results further verified the applicability of the constitutive model established in this study.

Mg matrix composites were often reinforced by non-deformable ceramic particles. In this paper, a novel Mg matrix composite reinforced with deformable TC4 (Ti–6Al–4 V) particles was fabricated and then extruded. The evolutions of microstructure and mechanical properties of the composite during hot extrusion were investigated. Hot extrusion refined grains and eliminated the segregation of TC4 particles. TC4 particles, as deformable particles, stimulated the nucleation of dynamic recrystallization during extrusion. However, since the deformation of TC4 particles partly released the stress concentrations around them, the recrystallized grains are just slightly smaller around TC4 particles than that away from them, which is evidently different from the case in Mg matrix composites reinforced by non-deformable ceramic particles. Compared with AZ91 matrix composites reinforced by SiC particles, the present composite possesses the superior comprehensive mechanical properties, which are attributed to not only the strong interfacial bonds between TC4p and matrix but also the deformability of TC4 particles.

The research on hot deformation including flow behavior, microstructure evolution via EBSD method and the constitutive characteristic model of hot extruded GH738 alloy fabricated by spray forming was conducted by using Gleeble-3500TM simulator at the temperature range of 950~1150 ℃, strain rate range of 0.001~1 s–1 and engineering strain of 50%. The results show that the flow stress decreases with increasing of the deformation temperature and decreasing of the strain rate. The peak flow stress of coarse grain GH738 is higher than that of fine grain within the extruded GH738 alloy. The activation energy Q of extruded GH738 alloy is 651.08 kJ·mol–1. The hot deformation activation energy Q of GH738 alloy is tending to increasing with the decreasing of the original average grain size. The microstructure evolutes from original stretched grain to equiaxed grain with the increasing deformation temperature through the onset of recrystallization. The full dynamic recrystallization microstructure is obtained at the temperature above 1000 ℃ and the microstructure tend to coarsen with the higher deformation temperature.

In contrast with titanium (Ti) alloys, the α+β region for commercially pure Ti is neglectable. Therefore, its β transus (Tβ) can be regarded as a watershed for β-Ti and α-Ti. Utilizing this characteristic, we fabricated dual-textured Ti extrudates through a powder metallurgy route via manipulating the hot extrusion temperature. The crystallographic texture along extrusion direction (ED) was analyzed. Different from the sole //ED texture throughout the entire extrudate in previous studies, our extrudates exhibited unique dual-textured microstructure. The firstly extruded portion manifested //ED and //ED, whereas the rest extrudate displayed //ED. This was attributed to the realtime extrusion temperature of each location in comparison with Tβ. On the other hand, the last portion of the extrudate contained much more interstitial nitrogen and oxygen, which led to extremely high strength via solid solution strengthening. This was resulted from a combination effect of diffusion-controlled element absorbing and material flow during extrusion. Our findings may open up a new direction in developing high-performance materials with variable microstructure and mechanical properties for medical applications like neoarthrosis.

Due to high rice consumption, food insecurity can negatively impact health; hence, food diversification is considered an appropriate solution for achieving national food security. Artificial rice production using local natural resources will support food sustainability in Indonesia. Sago, arrowroot tuber, and mung bean flours were the main ingredients for producing artificial rice using the hot extrusion method. The effects of composite flour composition and extrusion temperatures on the nutritional value (carbohydrate, protein, fat, and fiber), morphological structure (scanning electron microscopy analysis), thermal stability (differential scanning calorimetry analysis), and acceptability of artificial rice were investigated in this study. The results showed that the best composition was obtained when using a combination of 50% (w/w) sago flour, 30% (w/w) arrowroot tuber flour, and 20% (w/w) mung bean flour. The results of chemical analysis showed that the best artificial rice in this study contained 11.18% water content, 80.27% carbohydrates, 5.14% protein, 0.46% fat, and 5.14% crude fiber. The product contained sufficient fiber and carbohydrate content to be an appropriate staple food. The best extrusion temperature was 85 °C. Moreover, the differential scanning calorimetry profiles showed that artificial rice began undergoing physical changes at approximately 100 °C. Importantly, the color, texture, aroma, and taste of the cooked artificial rice were accepted by consumers.

2A12 aluminum alloy is a high-strength aerospace alloy. During its extrusion process, the extrusion process parameters have a great impact on the microstructure evolution of the extruded products. There are three extrusion process parameters controlled in the actual project, which are the initial temperature of billet, the initial temperature of die and the extrusion speed. Combined with a back propagation (BP) neural network and finite element method (FEM) simulation, based on the constitutive equation and recrystallization evolution process of 2A12 aluminum alloy, this paper establishes a prediction model for the grain size of extruded pipe by these three extrusion process parameters. This paper used a 35MN extruding machine for a production verification of 2A12 pipe. The results show that the predicted grain size is 3% smaller than the actual size.

TiB _2 /2024 aluminum matrix composites were prepared in situ from the Al–K _2 TiF _6 –KBF _4 reaction system; then, we investigated the microstructure and mechanical properties of the composites in the as-cast and extruded states. X-ray diffraction (XRD) and scanning electronic microscope (SEM) analyses showed that TiB _2 particles were successfully produced in the matrix by the in situ reactions. The optimal content of TiB _2 particles in the composites was 3 wt%; moreover, the size of α -Al grains in the microstructure of the composites with 3 wt% content was the smallest among the composites reinforced with different content of TiB _2 particles, and the TiB _2 particles showed a uniform distribution. The tensile strength and elongation of the composites (246 MPa and 9.8%, respectively) were 21.8% and 18.1% higher compared with those of the alloy matrix. When the TiB _2 particle content was 5 wt%, the cast composite exhibited the highest hardness of 113 HBW, which was 43.0% higher than that of the base alloy. Fracture analysis showed that the fracture mode changed from ductile to brittle as the mass fraction of TiB _2 in the composite increased. The mechanical properties of the 3 wt% TiB _2 /2024 aluminum matrix composite were significantly improved after hot extrusion, with tensile strength and elongation values of 375 MPa and 19.7%, respectively, which were 52.4% and 101% higher than those of the as-cast material.