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This study focuses on the preparation and characterization of zinc-based alloys containing magnesium, calcium, and manganese. The alloys were prepared by the melting of pure elements, casting them into graphite molds, and thermo-mechanically treating them via hot extrusion. The phase compositions of the samples were analyzed using X-ray diffraction technique and SEM/EDX analysis. The analysis confirmed that in addition to the Zn matrix, the materials are reinforced by the CaZn13, MgZn2, and Mn-based precipitates. The mechanical properties of the alloys were ascertained by tensile, compressive, and bending tests, measurement of the samples microhardness and elastic modulus. The results indicate that an increase in Mn content leads to an increase in the maximum stress experienced under both tension and compression. However, the plastic deformation of the alloys decreases with increasing Mn content. This study provides valuable insights into the microstructural changes and mechanical behavior of zinc-based alloys containing magnesium, calcium, and manganese, which can be used to design alloys for specific biomedical applications.

Al-Ti-C-(Ce) grain refiners were prepared by combining in-situ reaction, hot extrusion, and adding CeO2. The effects of second phase TiC particle size and distribution, extrusion ratio, and Ce addition on the grain-refining performance of grain refiners were investigated. The results show that about 10 nm TiC particles are dispersed on the surface and inside of 100–200 nm Ti particles by in-situ reaction. The Al-Ti-C grain refiners, which are made, by hot extrusion, of a mixture of in-situ reaction Ti/TiC composite powder and Al powder, increase the effective nucleation phase of α-Al and hinder grain growth due to the fine and dispersed TiC; this results in the average size of pure aluminum grains to decrease from 1912.4 μm to 504.8 μm (adding 1 wt.% Al-Ti-C grain refiner). Additionally, with the increase of the extrusion ratio from 13 to 30, the average size of pure aluminum grains decreases further to 470.8 μm. This is because the micropores in the matrix of grain refiners are reduced, and the nano-TiC aggregates are dispersed with the fragmentation of Ti particles, resulting in a sufficient Al-Ti reaction and an enhanced nucleation effect of nano-TiC. Furthermore, Al-Ti-C-Ce grain refiners were prepared by adding CeO2. Under the conditions of holding for 3–5 min and adding a 5.5 wt.% Al-Ti-C-Ce grain refiner, the average size of pure aluminum grains is reduced to 48.4–48.8 μm. The reason for the excellent grain-refining and good anti-fading performance of the Al-Ti-C-Ce grain refiner is presumedly related to the Ti2Al20Ce rare earth phases and [Ce] atoms, which hinder agglomeration, precipitation, and dissolution of the TiC and TiAl3 particles.

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.

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.

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.

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.

Za izboljšanje gospodarnosti toplega iztiskanja Al profilov je za inženirjev v praksi podaljšanje življenjske dobe orodij pomembna naloga saj ima orodje pomembno postavko pri ceni iztiskanega profila. Nastanek razpok, obraba, krušenje nitridnih plasti, plastična deformacija, lomi, itd., so najpogostejši vzroki za odpoved orodij, ki ne zagotavljajo več doseganje zahtev kupca glede kvalitete iztiskanih profilov. Katera od poškodb bo odločilno vplivala na življenjsko dobo orodja je odvisno od konstrukcije orodja, kvalitete materiala orodnega jekla, obremenitev in tehnoloških deformacijskih parametrov, izbranih parametrov nitriranja (nitridiranje), vzdrževanja, itd., i.e. gre za kompleksen problem. Izboljšanje obrabne obstojnosti drsnih površin je pomembno za podaljšanje življenjske dobe orodji pri čemer se večinoma uporablja postopek plinskega nitriranja. Ta postopek v času služenja orodja lahko tudi večkrat ponovimo. Na izbranih orodjih za toplo iztiskanje Al je bila opravljena analiza vzrokov za nastalo poškodbo ter rekonstrukcija njihovega razvoja ter tako tudi predlagane izboljšave za podaljšanje življenjskih dob analiziranih orodij. Prekomerno izločanje nitridov na kristalne meje je posledica nepravilnih parametrov nitriranja, to so čas, temperatura in potencial nitriranja. To vodi do pokanja nitridov in s tem njihovega hitrejšega adhezijskega odnašanja delov zrn z površine. Na drsnih površinah matric in trnov prevladujejo različni kontaktni pritiski, kar vodi do lokalnega povečanja obrabe na področjih maksimalnih kontaktnih pritiskov. Proces obrabe se nadaljuje z tvorbo majhnih brazd med adhezijsko odnešenimi plastmi s površine ter njihovim podaljševanjem v smeri drsenja materiala, ter tudi lateralnim širjenjem brazd oz. tvorbe žleba v lateralni smeri. Ob lateralnem dotiku dveh vzporednih brazd v smeri drsenja materiala se nam začne tvoriti žleb tudi v lateralni smeri, ki z nadalnjim razvojem obrabe vodi do tvorbe daljšega žleba po obodu drsne površine. Extending the die service time is for engineers in practice an important task for improvement the economy of hot extrusion of Al profiles since the dies have an important proportion in the price of the extruded profile. The formation of cracks, wear, crushing of nitride layers, plastic deformation, fractures, etc., are the most common causes of failure of dies, i.e. the time when used dies can not ensure the customer's requirements regarding the quality of extruded profiles, i.e. dimension tolerances, surface finish and mechanical properties. Which of the damages will be decisive at service time of dies depends on the construction of the dies (Al flow), the quality of die steels, loads and technological deformation parameters, selected parameters of nitriding, maintenance, etc., i.e. it is a complex problem. Improving the wear resistance of the sliding surfaces is important for extending the die service time whereas gas nitriding process is mostly used for improving of wear resistance of bearing surface. The process of nitriding can be repeated several times during the service lime of dies. An analysis of the causes leading to damages and a reconstruction of their development on selected dies for hot extrusion of Al were performed as well as improvements for extension of service time of the analysed dies are given. Excessive occurrence of nitrides on grain boundaries is the result of improper nitriding parameters, i.e. time, temperature and nitriding potential. This leads to the cracking of nitrides on grain boundaries and thus to accelerated adhesive removal of small parts from die bearing surface. Different contact pressures prevail around the perimeter of the bearing surface of dies and mandrels higher contact pressures leads to increase of wear, i.e. increased density of adhesive removed parts (craters) from bearing surface. The wear progress continues with the formation of small furrows between the adhesively removed craters from the surface and their lengthening in the direction of aluminium sliding, as well as the lateral expansion of the furrows or formation of the groove in the lateral direction. Upon lateral contact of two parallel furrows in the direction of sliding of the material, a groove begins to form in the lateral direction as well, which with further development of wear leads to the formation of a longer groove around the perimeter of the bearing surface.

(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.

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.

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.

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.

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. 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

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.

The paper addresses issues of interest related to the uniform distribution of the reinforcement phase and the continuity of the metal matrix, for two ways of obtaining the powder composites, the hot extrusion and the spark plasma sintering (SPS) respectively. The reinforcement phase is the nickel aluminides obtained by mechanical alloying in ball mills, and the metal matrix is made of aluminum powders. Prior to extrusion, the mixture of aluminum powders and nickel aluminides was pressed and subsequently sintered in environments with high carbon potential, so that in the final product, nickel aluminides, carbide and aluminum oxides were found as reinforcement phases. The obtained results confirmed the hypothesis that, from a blank product with a random distribution of the reinforcement phase, a product with an ordered distribution of the reinforcement phase is obtained after extrusion and that for the same initial proportion of nickel aluminides as reinforcement phase, the composite hardness obtained by hot extrusion is higher compared to that obtained by SPS, the difference being determined by the increase of the proportion of the reinforcement phase by the appearance of aluminum carbide and aluminum oxides during the sintering operation in the high carbon environment.

In this work, tensile tests were conducted on two powder metallurgy materials based on the AZ31 magnesium alloy. The first material, named AZ31-PM, was processed using atomized powder, followed by isostatic cold compaction at 340 MPa, plus hot extrusion at 350 °C. The second material, named AZ31-PMCM, used metal powder that was cryomilled in liquid nitrogen environment and processed as for the AZ31-PM material. Creep mechanisms were analyzed in the range 300 °C to 400 °C based on the creep laws determined previously for ingot metallurgy AZ31. Two threshold stresses, one for grain boundary sliding and the other for slip creep, both independent of temperature, were introduced, providing a consistent description of creep for the different AZ31-based materials. The variations observed in threshold stresses in the AZ31-PM material were attributed to an inhomogeneous distribution of dispersoids and satisfactorily explained by a composite type model. This method of analyzing the data is compared with the traditional one in the literature, demonstrating that the dependence of the threshold stresses with the temperature, reported in those articles, could actually be derived from the method used rather than from a real physical effect., The authors acknowledge the financial support of CICYT, Spain, under Programs MAT2012-38962 and MAT2015-68919 (MINECO/FEDER).

Цель работы – разработка Ñ‚ÐµÑ Ð½Ð¾Ð»Ð¾Ð³Ð¸Ð¸ изготовления Ñ‚Ð¸Ð¿Ð¾Ð²Ñ‹Ñ Ð¿Ð¾ÐºÐ¾Ð²Ð¾Ðº типа ÑÑ‚ÑƒÐ¿ÐµÐ½Ñ‡Ð°Ñ‚Ñ‹Ñ Ð²Ð°Ð»Ð¾Ð² методом горячего выдавливания при локальном нагреве на основе компьютерного моделирования.Объект исследования – типовая деталь «Вал ступенчатый», материал: сталь 35ХГСА ГОСТ 4543–2016.На основе расчетов и моделирования в комплексе DEFORM определены основные Ñ‚ÐµÑ Ð½Ð¾Ð»Ð¾Ð³Ð¸Ñ‡ÐµÑÐºÐ¸Ðµ параметры процесса. Разработан чертеж поковки, спроектирован штамп для выдавливания, предложена ÑÑ ÐµÐ¼Ð° автоматизации процесса, составлена маршрутная карта Ñ‚ÐµÑ Ð½Ð¾Ð»Ð¾Ð³Ð¸Ñ‡ÐµÑÐºÐ¾Ð³Ð¾ процесса и план производственного участка. Приведены способы оценки экономической эффективности процесса, меры безопасности при работе в Ð¿Ñ€ÐµÑÑÐ¾Ð²Ñ‹Ñ Ñ†ÐµÑ Ð°Ñ ., Objective: hot extrusion of standard stepped shaft type workpieces under local heating technology development based on computer modeling.The object of the research is the standard part «Stepped shaft» made of steel 35HGSA GOST 4543–2016.The main process parameters were defined based on calculating and modeling in DEFORM. The drawing of the forging was developed, the die for extrusion was designed, process automation scheme was proposed, process route map and workshop area map were planned. Methods of assessing economic efficiency of process and safety measures when working in forging workshops were shown.

Extrusion technology allows the preparation of analog rice, an artificial product made of carbohydrate sources other than rice, with characteristics similar to natural rice. In this study, we aimed at determining the effect of composition and temperature on the nutritional content of analog rice obtained using heat extrusion technology. The physical properties and acceptability of the resulting product were also studied. Skim milk, sago, mung bean, and corn flour as well as the binder carboxymethyl cellulose (CMC) were used. The procedure was conducted in four stages: raw-material preparation, formulation, physicochemical evaluation, and sensory property evaluation. The best analog rice formula was established as 50% sago flour, 30% corn flour, 19.2% mung bean flour, 0.4% skim milk, and 0.4% CMC. The panelists’ most preferred rice analog formula was the one with the highest sago starch and skim milk content. The extrusion temperature did not significantly affect the nutrient content. However, it had a considerable impact on the thermal profile and physical properties, such as appearance and granular morphology.

In this study, Ingots of (Bi, Sb)2Te3 thermoelectric material with p-type conductivity have been obtained by hot extrusion. The main regularities of hot extrusion of 30 mm rods have been analyzed with the aid of a mathematical simulation on the basis of the joint use of elastic-plastic body approximations. The phase composition, texture and microstructure of the (Bi, Sb)2Te3 solid solutions have been studied using X-ray diffraction and scanning electron microscopy. The thermoelectric properties have been studied using the Harman method. We show that extrusion through a 30 mm diameter die produces a homogeneous strain. The extruded specimens exhibit a fine-grained structure and a clear axial texture in which the cleavage planes are parallel to the extrusion axis. The quantity of defects in the grains of the (Bi, Sb)2Te3 thermoelectric material decreases with an increase in the extrusion rate. An increase in the extrusion temperature leads to a decrease in the Seebeck coefficient and an increase in the electrical conductivity. The specimens extruded at 450 °C and a 0.5 mm/min extrusion rate have the highest thermoelectric figure of merit (Z = 3.2 × 10−3 K−1).

The prior particle boundaries (PPBs), as one of the typical defects in the nickel-based powder metallurgy superalloy, largely affect the microstructure and thus properties/performance of alloys. However, the effect of PPBs on the microstructure evolution in nickel-based powder metallurgy superalloy during heat treatment is still unclear. In this paper, a comparative study of PPBs and their influence on grain growth during solution treatment in a novel nickel-based powder metallurgy superalloy FGH4113A (i.e., WZ-A3 from Shenzhen Wedge, China) with/without hot extrusion (HEX) was conducted. Firstly, through a combination of scanning electron microscope (SEM), electron probe microanalyzer (EPMA) and transmission electron microscope (TEM) techniques, PPBs in FGH4113A alloys were characterized to be Al2O3, carbides (TiC, M6C, M23C6) and large-size γ′ particles. After HEX, the oxides broke, carbides deformed, and γ′ phase redistributed. After solution treatment at 950 °C, the TiC decomposed to M6C and M23C6, while no such decomposition occurred in FGH4113A alloys after solution treated at 1050 °C and 1150 °C. Secondly, the evolution of grain size in FGH4113A alloys was analyzed using the electron backscattered diffraction (EBSD) technique. At 950 °C, the decomposition of carbide TiC resulted in the increase of PPBs and the enhancement of their pinning effect on grain boundaries, thus inhibiting grain growth. At 1050 °C, the nucleation rate due to recrystallization is comparable to the grain growth rate, leading to the stable distribution of grain size. While at 1150 °C, the higher temperature can induce a higher content of PPBs. However, the driving force for grain growth surpassed the pinning force of PPBs, making the grains quickly coarsen. Finally, it was concluded that the HEX process is an effective method to modify the microstructure of powder metallurgy superalloy after HIP that can heavily refine the grains in the powder metallurgy superalloys. Furthermore, based on the present experiment and analysis, an appropriate solution treatment mechanism (i.e., 1050 °C for 2 h) was proposed for FGH4113A alloys.

In this work, Mg-4Zn-1Ca (wt. %) alloy was primarily processed by disintegrated melt deposition. The resulting ingots were further pre-processed by the turning induced deformation technique (TID), and the turnings were subsequently consolidated by the hot extrusion process and sinterless powder metallurgy. A range of extrusion temperatures (200, 250 and 300 °C) was tested to understand the effect of the extrusion temperature on tailoring the microstructure and properties of TID-processed Mg-4Zn-1Ca (wt. %) alloys. The results indicated that the combined effect of TID and extrusion temperature plays a significant role in grain refinement, specifically at 200 °C. Overall, the sample extruded at 300 °C showed the best microhardness and compressive yield strength values. The resistance to ignition and wet corrosion increased and decreased, respectively, when the extrusion temperature was increased. Variations of basal texture and fine grain strengthening due to variations of extrusion temperature led to different properties peaking at different extrusion temperatures. Microstructure-property relationships are therefore discussed, highlighting that different extrusion temperatures have characteristic effects in improving and lowering the properties. Many of the investigated properties of TID-processed alloys exceed that of commercial Mg alloys, suggesting the capability of the sinterless TID technique to develop as an economical industrial way of recycling and manufacturing magnesium-based materials.

Direct solid-states, such as hot extrusion and equal channel angular pressing (ECAP), are alternative and efficient solid-state processes for use in recycling aluminium scrap. These processes utilise less energy and are eco-friendly. Ceramic particles such as ZrO2 are suggested as alternatives in the production of metal composites. This study investigated and optimised the effects of various parameters of reinforced ZrO2 nanoparticles on the mechanical and physical properties via response surface methodology (RSM). These parameters were the volume fraction (VF), preheating temperature (T), and preheating time (t). The effects of these parameters were examined before and after the heat treatment condition and ECAP. Each parameter was evaluated at varying magnitudes, i.e., 450, 500, and 550 °C for T, 1, 2, and 3 h for t, and 1, 3, and 5% for VF. The effect that process variables had on responses was elucidated using the factorial design with centre point analysis. T and VF were crucial for attaining the optimum ultimate tensile strength (UTS) and microhardness. Reducing VF increased the mechanical properties to 1 vol% of oxide. The maximum hardness of 95 HV was attained at 550 °C, 1.6 h, and 1 vol% ZrO2 with a density of 2.85 g/cm3 and tensile strength of 487 MPa. UTS, density, and microhardness were enhanced by 14%, 1%, and 9.5%, respectively. Additionally, the hot extrusion parameters and ECAP followed by heat treatment strengthened the microhardness by 64% and density by 3%. Compression pressure and extrusion stress produced in these stages were sufficient to eliminate voids that increased the mechanical properties.

In this paper, the extrusion process of titanium seamless tubes was studied using several finite element (FE) analyses. First, the finite element result was compared with experimental extrusion data acquired to validate the current analysis. Then, the effect of design parameters of the die shape was numerically analyzed using commercial FE software, Forge NxT, for the metal forming process. Elastic FE analyses were also conducted for dies to analyze the maximum principal stress that affects the early fracture of dies during the extrusion process and the maximum von Mises stress that causes the severe deformation of dies. Consequently, the effect of the corner radius at the exit and land length on the extrusion load and die stress is negligible compared to that of the corner radius at the entrance and die angle. Finally, we suggested a die angle of 60° and a corner radius at the die entrance between 10 and 15 mm as an optimal design for the current extrusion process.

Major advantage of extruded Bi2Te3 based thermoelectric materials is high mechanical strength compared with that of melt-crystallized materials. Mechanical properties are of special importance for thermogenerator module applications where thermogenerator branches may undergo elevated thermal stresses due to large temperature differences at the modules. Since extrusion is typically a high-temperature process the structure of extruded materials is controlled by the plastic deformation in multiple slip systems resulting in the formation of a final deformed structure. The grain orientations are predominantly such that the most probable cleavage plane orientation is parallel to the extrusion axis. Recovery processes occur simultaneously and different recrystallization stages may take place. In the latter case the deformed texture may be destroyed. Structure evolution along the extruded rod of Bi2Se0.3Te2.7 ternary solid solution was studied with metallography and X-ray diffraction. Extrusion was interrupted for the study and so the specimen was a whole rod the initial part of which was the extrusion billet and the final part was the as-extruded material. The structure of the material is formed by competitive processes of dislocation generation and annealing. The plastic deformation energy is the highest in the extruder zone of the rod. Both the hardening processes and the texture are controlled by the plastic deformation mechanism. Plastic deformation is accompanied by generation of defects that are most likely vacancy type ones.

Multi-pass hot extrusion was used to prepare the Al2O3/AZ31 composite.The microstru-cture was characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy, and mechanical properties were tested by Vickers hardness tester and electron universal strength tester. The results show that Al2O3 particles are uniformly distributed in AZ31 magnesium matrix by multi-pass hot extrusion. The grain refining effect of Al2O3 particles on the matrix is enhanced, and the grain size of the composite decreases significantly with the increase of the pass. During the hot extrusion process, the dislocation density around the Al2O3 particles increases, and the high-density dislocation region facilitates the dynamic recrystallization nucleation, so that the grains of the Al2O3/AZ31 composite are significantly refined. The Al2O3 particles are gradually distributed into a long strip from the initial island distribution, then distributed in a linear pattern, and finally distributed uniformly in the form of particles in the AZ31 magnesium matrix. After fourth-pass hot extrusion, the mechanical properties of Al2O3/AZ31 composite are significantly improved, and hardness, tensile strength and yield strength are 89HV, 305MPa and 198MPa, respectively. The hardness, tensile strength and yield strength increase by 19.2%, 14.8%, and 14.1%, respectively, compared with the first-pass hot extrusion.

The large-sized (?300 mm) nickel based superalloy GH738 billet was fabricated by spray forming followed by hot isostatic press (HIP) and hot extrusion (HEX) within varied deformation temperatures. The micro-defect, carbonitride distribution, γ/γ′ evolution during the hot processes were investigated by the relevant approaches including XRD, SEM, TEM, EBSD and phase analysis technique respectively. The results show that the porosities in γ matrix of spray deposited billet are welded up to closure after HIP process. The difference of characteristic microstructure after dynamic recrystallization obtained after the hot extrusion is mainly based on the varied deformation conditions including temperature and strain-stress state. The grain-boundary-distributed carbonitrides in HIPed billiet are transformed into extrusion-direction-along distribution after hot extrusion. The effects of temperature field delivered and cooling condition on elements constitution, mass fraction, morphology, size and distribution of γ′ in GH738 are validated during different hot processes as well.

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.

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.

In the present research, a Mg–4Zn–1.2Y–0.8Nd (wt.%) alloy was heat treated and hot extruded with different passes. XRD, SEM, TEM and tensile testing were employed to characterize the microstructure evolution and mechanical properties. The results exhibited that the semi-continuously distributed W-Mg3Zn3Y2 phases formed the skeleton structure which separated the α-Mg matrix into a dual-size grain structure. In addition, the Mg24Y5, Mg41Nd5 and Y2O3 phase was also observed in the heat-treated alloy. Moreover, it was found that the Mg24Y5 phase had an orientation relationship with the α-Mg matrix of α[111]Mg24Y5//[0001]α-Mg and α(101¯)Mg24Y5//(101¯0)α-Mg, and the Mg41Nd5 phase had an orientation relationship with the α-Mg matrix of α[001]Mg41Nd5//[0001]α-Mg. The one-pass hot extrusion segmented the secondary phases into small ones and refined the α-Mg matrix. Due to the partly recrystallization and crystal orientation difference, the coarse elongated grain surrounded by fine recrystallized grain and secondary phase was the main feature of the one-pass hot extruded alloy. Furthermore, the secondary phases exhibited the linear distribution along the direction of hot extrusion. The two-pass hot extrusion refined the secondary phase and matrix further, which produced the ultrafine α-Mg matrix with uniform grain size and a well redistributed secondary phase. Due to the microstructure optimization by the multi-pass hot extrusion, the ductility and strength of the Mg–Zn–Y–Nd alloy were well improved, especially the two-pass hot extruded alloy which was significant improved in ductility and strength simultaneously.

В Ñ Ð¾Ð´Ðµ данной работы были рассмотрены наиболее приемлемые методы компактирования алюминия с редкоземельными элементами. Введение добавок РЗЭ придает материалам целый набор ÑƒÐ½Ð¸ÐºÐ°Ð»ÑŒÐ½Ñ‹Ñ ÑÐ²Ð¾Ð¹ÑÑ‚Ð²: повышаются прочностные Ñ Ð°Ñ€Ð°ÐºÑ‚ÐµÑ€Ð¸ÑÑ‚Ð¸ÐºÐ¸ материалов, увеличивается диапазон температур Ð¸Ñ Ð¸ÑÐ¿Ð¾Ð»ÑŒÐ·Ð¾Ð²Ð°Ð½Ð¸Ñ и т. д. В обозримом будущем редкоземельные элементы будут привлекать значительное внимание, и спрос на Ð½Ð¸Ñ , вероятно, будет расти. В Ñ€Ð°Ð¼ÐºÐ°Ñ Ñ€Ð°Ð±Ð¾Ñ‚Ñ‹ было подобрано соотношение чистого алюминия и Ð¼ÐµÑ Ð°Ð½Ð¸Ñ‡ÐµÑÐºÐ¸ легированного алюминия + РЗМ позволяющее компактировать данную композицию методом горячей экструзии. Полученное соотношение позволило изготовить качественную заготовку с ценным набором свойств. В работе также представлены результаты исследований влияния Ð¼ÐµÑ Ð°Ð½Ð¸Ñ‡ÐµÑÐºÐ¾Ð³Ð¾ легирования Ñ€ÐµÐ´ÐºÐ¾Ð·ÐµÐ¼ÐµÐ»ÑŒÐ½Ñ‹Ñ ÑÐ»ÐµÐ¼ÐµÐ½Ñ‚Ð¾Ð² в алюминиевые сплавы, а также влияние РЗМ на свойства алюминия, Ñ‚Ð°ÐºÐ¸Ñ ÐºÐ°Ðº твердость и пластичность. Было проведено два режима экструзии и в результате 2 образца (с оболочкой АМг5 и без оболочки). В результате выяснилось, что горячая экструзия в оболочке позволяет получить заготовки с качественной Ð¿Ð¾Ð²ÐµÑ€Ñ Ð½Ð¾ÑÑ‚ÑŒÑŽ, по сравнению с экструзией без оболочки. Благодаря последующей пластической деформации было выявлено, что помимо удлинения на образце экструдированном без оболочки наблюдалось залечивание Ð¿Ð¾Ð²ÐµÑ€Ñ Ð½Ð¾ÑÑ‚Ð½Ñ‹Ñ Ð´ÐµÑ„ÐµÐºÑ‚Ð¾Ð² – трещин. А наличие оболочки многократно увеличивает пластичность образцов при Ð¸ÑÐ¿Ñ‹Ñ‚Ð°Ð½Ð¸ÑÑ Ð½Ð° растяжение., In this work, the most acceptable methods of compacting with rare earth elements were considered. The introduction of REE additives gives the materials a whole set of unique properties: increased strength characteristics of materials, increases the temperature range of their use, etc. Rare earths will receive significant attention for the foreseeable future, and the demand for them is likely to grow. Within the framework of the work, the ratio of pure aluminum and mechanically alloyed aluminum + REM was selected, which makes it possible to compact this composition by hot extrusion. The resulting ratio made it possible to produce a high-quality workpiece with a valuable set of properties. The paper also presents the results of studies of the effect of mechanical alloying of rare earth elements in aluminum alloys, as well as the effect of rare earth metals on the properties of aluminum, such as hardness and ductility. Two modes of extrusion were carried out and, as a result, 2 samples (with AMg5 shell and without shell). As a result,it was found that hot sheathed extrusion produces preforms with a good surface compared to bare extrusion. Due to the subsequent plastic deformation, it was revealed that, in addition to elongation, on the extruded sample without a shell, there was observed healing of surface defects - сracks. And the presence of the shell greatly increases the ductility of the samples during tensile tests.

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.

Homogeneous dispersion of high-content graphene nano-platelet (GNP) in metals is challenging due to the serious aggregation tendency of graphene. Traditional secondary processing such as extrusion usually has too limited shear strains to reach a desirable GNP dispersion state. Our previous work demonstrated that 1.0 vol% GNP/Al composite was successfully produced via multiple wire-drawing at ambient temperature. However, the fabrication of 5.0 vol% GNP/Al composite was not successful because of the limited cumulative shear strains. Here we described fully dispersed state of 5.0 vol% GNP in Al by hot-drawing at an elevated temperature 400 °C. The evolution of the microstructures and mechanical properties were investigated in relation to the number of drawing passes. The ultra-fine grains with size 372 nm were obtained via dynamic recrystallization after drawing for six passes (cumulative strain 94%). In particular, stripping of the GNP into thin layers and their preferential alignment in the wire axis occurred during the shear deformation. As a result, 5.0 vol% GNP/Al composite produced by six-pass drawing possessed improved yield strength (σs, 449 MPa) and ultimate tensile strength (UTS, 461 MPa). The results demonstrated the feasibility of dispersing high-content GNP in aluminum alloys by extrusion followed by multi-pass hot drawing techniques.

In the work, a method for assessing the value of deformation resistance during hot extrusion of tubes from nickel- based alloys, on tube-extrusion plants of various capacities, is developed. The case, the drawing coefficient for these conditions was 8, the degree of deformation was 87.5%, and the strain rate was 90 s-1. Using the developed method, the force parameters of the hot extrusion of tubes from nickel-based alloys can be calculated, which allows us to determine the possibility of extrusion them on existing and designed tube-extrusion equipment both by steel and alloy grades, and by tubes sizes.

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.

Al-10Zn-3.5Mg-2.5Cu/graphene nanocomposites were developed by a combination of liquid metallurgy and hot extrusion techniques. The effect of varying graphene content (0.1%, 0.3%, 0.7% and 1.0%) on microstructure and mechanical properties was studied in as cast, hot extruded and heat treatment conditions. The hot extruded nanocomposites showed uniform dispersion of graphene in matrix and mostly dispersed in the grain boundaries. With the increase in graphene content the grain size of as cast and hot extruded nanocomposites showed significant drop. The ultimate tensile strength of nanocomposites increased with the increase in graphene content up to 0.7% for both as cast and hot extruded conditions. Due to precipitation hardening the heat treated and hot extruded nanocomposites showed highest increment in strength. The fracture studies showed inter-dendritic cracking for alloy and mixed fracture mode failure for nanocomposites as main failure mechanisms. � 2018 The Society of Manufacturing Engineers Scopus

The effect of different Ti contents on the microstructures and tensile mechanical properties of the hot-extruded Cu-15Ni-8Sn alloys was investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy and tensile test. The results show that both ultimate tensile strength and yield strength increase significantly with the increase of Ti content, while elongation decreases. The addition of 0.02% (mass fraction, the same below) Ti facilitates the precipitation of γ-(Cu, Ni)3Sn phase, and thereby leads to a significant refinement of recrystallization grain. When the content of Ti increases to 0.3%, a small quantity of needle-like Ni3Ti phase is formed, which abates the effect of γ precipitates on inhibition of recrystallized grains growth. With the addition of up to 0.5% Ti, a larger amount of Ni3Ti precipitates are formed, which enhance the effect of recrystallized grain refinement; however, a few Ni3Ti precipitates become large and deteriorate the elongation of the alloy. In this study when 0.3% Ti is added, the mechanical properties of the alloy are preferable, where the tensile strength, yield strength and elongation are 875, 713MPa and 24.1% respectively.

In the present study, aluminum based metal matrix composites containing various amounts of boron nitride (BN) nanoparticulates (0, 0.5, 1.0 and 1.5 vol.%) were fabricated by using the powder metallurgy (PM) technique involving microwave sintering and hot extrusion process. The microstructure, physical, thermal, mechanical and damping characteristics of the extruded nanocomposites were investigated. Field emission scanning electron microscopy (FE-SEM) study shows the evenly distributed BN particles in Al matrix. Mechanical analysis indicates that the compression, hardness and tensile strength of Al-BN nanocomposites increases with increasing amount of BN content. Particularly, a significant improvement in the tensile strength (?36%) is achieved in Al-1.5 vol.% BN nanocomposite when compared to the pure aluminum (Al). This improvement strength can be attributed to the dispersion hardening of the Al matrix due to the presence of hard BN nanoparticles. Thermal analysis shows that the coefficient of thermal expansion (CTE) decreases with increasing amount of BN which may be ascribed to inherent low CTE of BN nanoparticles used as reinforcement. The addition of BN nanoparticulates enhanced the damping characteristics of pure Al with Al-1.5 vol.% BN nanocomposite exhibiting the maximum damping capacity and damping loss rate with a minimum change in elastic modulus. The improved combination of properties exhibited by Al-BN nanocomposites make them potential candidates for a wide spectrum of industries especially for weight critical applications. This publication was made possible by NPRP Grant 7-159-2-076 from the Qatar National Research Fund (a member of the Qatar Foundation). Scopus

To date, various studies have analysed the effects of reinforced ceramic on the properties of AA6061 recycled aluminum alloy chips, such as the tensile strength and fractography. However, a comprehensive analysis of the properties of hybrid composite with the addition of nano-silica oxide and nano-copper oxide reinforcements is still very limited. Therefore, this study aimed to optimise the factors comprising the preheating temperature (PHT), preheating time (PHti), and volume fraction (VF) of reinforcements then determine their impacts on the physical and mechanical properties of the recycled solid-state extruded composite aluminum chips. A total of 45 specimens were fabricated through the hot extrusion technique. The response surface methodology (RSM) was employed to study the optimisation at a PHT range of 450–550 °C with PHti of 1–3 h and VF of 1–3 vol% for both reinforcements (SiO2 and CuO). Moreover, a random forest (RF) model was developed to optimize the model based on a metaheuristic method to improve the model performance. Based on the experimental results the RF model achieve better results than response surface methodology (RSM). The functional quadratic regression is curvature and the tested variable shows stable close data of the mean 0 and α2. Based on the Pareto analysis, the PHT and VF were key variables that significantly affected the UTS, microhardness, and density of the product. The maximum properties were achieved at an optimum PHT, PHti, and VF of 541 °C, 2.25 h, 1 vol% SiO2 and 2.13 vol% CuO, respectively. Furthermore, the morphological results of the tensile fractured surface revealed the homogenous distribution of nano-reinforced CuO and SiO2 particles in the specimens’ structure.

Mg-Al-Ca-Mn alloys with Ca/Al ≥ 1 of AX33, AX44, and AX55 were prepared by combining three processes of water-cooling semi-continuous cast, homogenization heat treatment, and hot extrusion. The as-fabricated alloys translated into composites consisting of α-Mg solid solution + granular Al2Ca. These alloys exhibited some favourable properties such as a tensile strength of 324~350 MPa at room temperature and 187~210 MPa at elevated temperature of 423 K, an ignition temperature of 1292~1344 K, and so on. Variation trend between performance and content of Al and Ca is given in this paper. The result indicated that the emerged second-phase Al2Ca in the alloys was beneficial to the improvement in mechanical properties, heat resistance, flame retardation, and corrosion resistance.

In the present study, nano-sized SiC (0, 0.3, 0.5, 1.0 and 1.5 vol%) reinforced aluminum (Al) metal matrix composites were fabricated by microwave sintering and hot extrusion techniques. The structural (XRD, SEM), mechanical (nanoindentation, compression, tensile) and thermal properties (co-efficient of thermal expansion-CTE) of the developed Al-SiC nanocomposites were studied. The SEM/EDS mapping images show a homogeneous distribution of SiC nanoparticles into the Al matrix. A significant increase in the strength (compressive and tensile) of the Al-SiC nanocomposites with the addition of SiC content is observed. However, it is noticed that the ductility of Al-SiC nanocomposites decreases with increasing volume fraction of SiC. The thermal analysis indicates that CTE of Al-SiC nanocomposites decreases with the progressive addition of hard SiC nanoparticles. Overall, hot extruded Al 1.5 vol% SiC nanocomposites exhibited the best mechanical and thermal performance as compared to the other developed Al-SiC nanocomposites. 1 2017 Chinese Materials Research Society This publication was made possible by NPRP Grant 7-159-2-076 from Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. Scopus

Investigating the effect of Al2O3-TiB2/Fe complex reinforcement (CCMR) on the mechanical properties of aluminum composites was the goal of this study. For this purpose, the Al2O3-TiB2/Fe reinforcement powders were synthesizedduring milling and subsequent annealing. Different volume percentages of the produced reinforcement powders (1.25, 2.5 and 5 vol.%) were added to aluminum matrix, milled for 10 h and then hot extruded. The structural phasic and mechanical investigations of the specimens were carried out using X-ray diffraction, scanning electron microscopy and tensile test. The results showed that the metallic component (Fe rich phase) in this new type of reinforcement stuck the ceramic parts (Al2O3-TiB2) to aluminium matrix, and has an importance role in the flexibility of the product. The best volume percentage of CCMR in aluminium matrix was about 2.5%. This nanocomposite had a combination of strength and ductility of about 500 MPa and 6%, respectively. &nbsp

In this study, conditional average estimator neural networks (CAE NNs) were used for an analysis of the common influences of the cooling mode in relation to the ram speed, extrusion ratio, casting speed and casting temperature on the yield strength and the elongation of an extruded profile made from aluminium alloy (AA)6082. The obtained results from the analysis revealed very complex relationships between these parameters. In order to maximise the values for the yield strength and the elongation, the values for the ram speed, extrusion ratio, casting speed and casting temperature should be optimised in relation to the mode of cooling.

This paper studied the effect of extrusion on the microstructures and tensile properties of 4 vol.% 5 μm SiCp/Al2014 composites fabricated by stir casting. It has been found that extrusion could refine the α-Al grains, increase the distributed homogeneity of SiC particles, decrease the porosity of the composites, and improve the interfacial bonding strength. The tensile properties, especially the ductility, of the fine SiCp/Al2014 composites were significantly improved by extrusion. Compared with the as-cast 4 vol.% 5 μm SiCp/Al2014 composites, the yield strength, ultimate tensile strength, and fracture strain of the extruded composites increased from 242 MPa, 367 MPa, and 3.8% to 304 MPa, 530 MPa, and 11.2%, which were increased by 25.6%, 44.4%, and 195%, respectively.

The previous study conducted on the as-cast Mg-2Y-1Zn-0.6Zr alloy showed that the tensile strength, yield strength and elongation of the as-cast alloy were 245 MPa, 135 MPa and 14.4%, respectively. In order to further explore the potential of the material, the hot extrusion process of variable temperature (250 &deg, C, 300 &deg, C and 350 &deg, C) was carried out on the basis of the as-cast alloy. After hot extrusion, the mechanical properties of the material have been greatly improved compared with as-cast alloy. The tensile strength, yield strength and elongation of the extruded alloy reached 327 MPa, 322 MPa and 24.9%, respectively. The reason for the significant improvement of material properties is mainly due to the dynamic recrystallization during thermal processing, which greatly fines the grains of as-cast alloy. Moreover, the experimental results shown that the corrosion performance of the alloy after hot extrusion at 300 &deg, C is also optimal.

The possibility of producing profiles directly by hot extrusion of aluminum chips, normally considered as scrap, is a promising alternative to the energy-intensive remelting process. It has to be taken into account that the mechanical properties depend on the quality of the weld seams between the chips, which arise during the extrusion process. To estimate the influence of the weld seams, quasistatic and cyclic investigations were performed on chip-based profiles and finally compared with cast-based extruded profiles. In order to gain comprehensive information about the fatigue progress, different measurement techniques like alternating current potential drop (ACPD)-technique, hysteresis measurements, and temperature measurements were used during the fatigue tests. The weld seams and voids were investigated using computed tomography and metallographic techniques. Results show that quasistatic properties of chip-based specimens are only reduced by about 5%, whereas the lifetime is reduced by about a decade. The development of the fatigue cracks, which propagate between the chip boundaries, was characterized by an intermittent testing strategy, where an initiation of two separate cracks was observed., Materials;12(15)

Hot extrusion is employed to produce bulk ZnSb and Zn13Sb10 thermoelectric materials. The extrusion parameters are optimized to achieve high purity products with high density and acceptable mechanical strength for further fabrication processing. Microstructural analysis is performed to investigate the products. X-ray diffraction, energy dispersive X-ray spectroscopy, and differential scanning calorimetry show high stability of the ZnSb phase during the extrusion that lead to high purity products. However, the Zn13Sb10 compound decomposes during the extrusion, yielding a bulk sample consisting of several other phases. Hot extrusion shows a great potential for scaled up production of high quality ZnSb thermoelectric materials.

Hot extrusion is employed to produce bulk ZnSb and Zn13Sb10 thermoelectric materials. The extrusion parameters are optimized to achieve high purity products with high density and acceptable mechanical strength for further fabrication processing. Microstructural analysis is performed to investigate the products. X-ray diffraction, energy dispersive X-ray spectroscopy, and differential scanning calorimetry show high stability of the ZnSb phase during the extrusion that lead to high purity products. However, the Zn13Sb10 compound decomposes during the extrusion, yielding a bulk sample consisting of several other phases. Hot extrusion shows a great potential for scaled up production of high quality ZnSb thermoelectric materials.

The magnesium matrix composite reinforced with 3 vol. % of short carbon fibers (Csf), fabricated, under industrial conditions, by the stir casting method, was applied to obtain composite bars by two extrusion methods: the novel method of cold severe plastic deformation with a forward-backward rotating die (KoBo) and conventional extrusion at 400 &deg, C. The effect of Mg(&alpha, ) grain refining, as well as fibers behavior and phenomenon at the fiber-matrix interface, was examined by optical microscopy, scanning electron microscopy with energy dispersive spectroscopy and scanning-transmission electron microscopy methods. The Mg(&alpha, ) grain quantitative characteristics revealed a decrease of the equivalent diameter from 219 &plusmn, 76 &mu, m (as-cast) to 24 &plusmn, 10 &mu, m and 0.89 &plusmn, 0.35 &mu, m (the hot-extruded and KoBo-processed, respectively). In addition, due to the KoBo application, except for the Csf orientation that was parallel to the extrusion direction, an effect of fibers fragmentation on the length of few Csf diameters was detected. No significant changes in the Csf-matrix interface (besides those between new carbon surfaces) formed by fibers fragmentation, and the matrix created by extrusion were detected. A comparison of the mechanical properties of the Mg-Csf composite showed that the KoBo method ensured a spectacular increase in strength and plasticity.