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"The 7075 aluminum alloy (a typical Al–Zn–Mg–Cu alloy) is one of the most important engineering alloys. It is mainly used in the automotive industry, in transport and aeronautics, due to its excellent strength/weight ratio. The purpose of the present research is to model the behavior of 7075 aluminum alloy and to build an experimental database to identify the model parameters. Firstly, the paper presents an experimental device of simple tensile tests and the studied material on 7075 aluminum alloy. Thus, uniaxial tensile tests are carried out in three loading directions relative to the rolling direction. From experimental hardening curves and Lankford coefficients, the mechanical properties are extracted, particularly the various fractures owing to pronounced anisotropy relating to the material. Secondly, plastic anisotropy is then modeled using the identification strategy which depends on yield criteria, hardening and evolution laws. By smoothing experimental hardening curves in the tensile tests, a selection is made in order to choose the most appropriate hardening law for the identification of the studied material. Finally, a comparison with experimental data shows that the behavior model can successfully describe the anisotropy of the Lankford coefficient."

"Aluminum alloys, such as A6061-T6, are widely used in engineering components. However, detailed knowledge is needed to understand the way they respond to a fracture due to mechanical loading. Fractures occur in the structural component from crack propagation, and it is important to understand the mixed mode fracture behavior of crack growth. In this research, mixed mode fracture testing was conducted on the aluminum alloy A6061-T6 by employing a compact tension shear specimen. Crack growth behavior was investigated by applying a quasi-static loading at a constant cross-head speed using a Servopulser universal testing machine. The crack growths were observed by a Keyence digital microscope, and the critical stress intensity factors of the material were examined. Results showed that the shear type of crack initiation preceded the opening-type fracture. The dimple-type fracture on the fracture surface occurred under mode I and mixed mode with a loading angle of about 60o and 75o, respectively. The transition of crack initiation behavior from the opening-type fracture to the shear-type fracture occurred at a loading angle from 15o to 30o. The experimental data followed the maximum hoop stress criterion under mode I and mixed mode at a loading angle 60o and 75o, respectively, for the compact tension shear specimen. Crack propagation behavior with three small holes occurring in a zigzag pattern ahead of the crack tip showed that crack initiation and propagation occurred only in the opening-type fracture. The experimental data followed the maximum hoop stress criterion under mode I and mixed mode with a lower mode II component at a loading angle of 75o. When the small holes occured inline, there were two types of fractures occurring: an opening fracture at crack initiation and then crack propagation caused by shear fracture."

"Aluminum alloy is one of the materials found in many applications, especially for electrical conductor materials. AlZrCe alloy reinforced by Al2O3 nanoparticles with Mg addition is proposed as one of the alternative materials to replace Aluminum Conductor Steel Reinforced (ACSR) as an aluminum conductor. Aluminum alloy Al-0.12%Zr-0.15%Ce as a master alloy was added with various weights of magnesium (Mg) from 2 to 5 wt% and was reinforced with 1.2% volume fraction of Al2O3 nanoparticles with particle sizes less than 80 nm. The molten metal matrix was blended with the reinforcement by a stirrer with a rotational speed of 500 rpm at a temperature of 750oC in an argon gas environment and casted by gravity casting. The objective of this research was to investigate the effect of magnesium on microstructural changes, electrical conductivity, and mechanical properties, such as tensile strength and hardness of the composites. The microstructure observation results showed that the greater the Mg content in composites up to 5%, the smaller the grain size of the composite matrix, wherein the grain size of the composite without Mg is 28 ?m, while the grain size of the composite with Mg of 2%, 3% and 5% are 27 ?m, 17 ?m and 9 ?m respectively. Similarly, tensile strength and hardness increased with increasing levels of Mg to 5% where the addition of 5% Mg, the tensile strength increased from 106 to 204 MPa and hardness increased from 30 to 68 BHN. In contrast, the electrical conductivity sharply decreased, due to the addition of Mg in the composite with a gradient of reduction, to 2.74% IACS (International Annealed Copper Standard) for every increasing 1% Mg. In which the electrical conductivity of the composite without Mg is 55.1% IACS and after adding 5 wt% Mg, it decreased to 41.3% IACS."

"Aluminum magnesium seri 5083 H112 banyak diaplikasikan untuk industri perkapalan. Hal tersebut dikarenakan aluminum memiliki kekuatan spesifik yang tinggi serta ketahanan korosi yang baik. Namun pada proses penyambungan berupa pengelasan banyak terjadi permasalahan berupa porositas serta menurunnya sifat mekanis terutama daerah terpengaruh panas. Mengacu kepada pengecoran, pemberian getaran pun diaplikasikan pada penelitian pengelasan dengan menggunakan kawat las ER 4043 ini. Sumber getaran berasal dari sebuah meja getar dan diatur getarannya sebesar 30 Hz. Pengujian yang dilakukan yakni pengujian tarik, metalografi, kekerasan mikro, radiografi-visual, dan image analysis. Dari hasil penggetaran nilai kekerasan daerah las dan juga kekuatan tarik meningkat dengan butir dari lasan yang halus pada tiap kecepatan las, 300 mm/menit dan 400 mm/menit. Jumlah porositas pun berkurang dengan dilakukannya penggetaran sebesar 30 Hz.

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5083 series aluminum magnesium is widely used for marine industrial. It is caused aluminum has high spesific strength and good corrosion resistance. However, at process of welding many of porosity occured in the aluminum and it decrease the mechanical properties especially in HAZ (Heat Affected Zone). At casting process of aluminum, there is one method that can reduce the porosity by giving vibration while casting is performed. So this method is tried to be aplicated at this research which is using ER 4043 as welding wire. Vibration that used is around 30 Hz. Tensile test, metallography, micro hardness, radiography-visual test, and image analysis was used for characterize mechanical properties and porosity content at weldment. The higher average result of tensile test and microhardness for ER 4043 filler weldment for vibrated specimen and porosity content decreased for specimen with welding speed 300 mm/minute and 400 mm/minute. And finer grain has found at microstructure of weldment after welded with vibration."

"Because lithium is the least dense elemental metal, materials scientists and engineers have been working for decades to develop a commercially viable aluminum-lithium (Al-Li) alloy that would be even lighter and stiffer than other aluminum alloys. The first two generations of Al-Li alloys tended to suffer from several problems, including poor ductility and fracture toughness; unreliable properties, fatigue and fracture resistance; and unreliable corrosion resistance.Now, new third generation Al-Li alloys with significantly reduced lithium content and other improvements are promising a revival for Al-Li applications in modern aircraft and aerospace vehicles. Over the last few years, these newer Al-Li alloys have attracted increasing global interest for widespread applications in the aerospace industry largely because of soaring fuel costs and the development of a new generation of civil and military aircraft. This contributed book, featuring many of the top researchers in the field, is the first up-to-date international reference for Al-Li material research, alloy development, structural design and aerospace systems engineering."

"Karena sifatnya yang menarik seperti ketahanan aus yang tinggi, koefisien ekspansi termal yang rendah, ketahanan korosi yang baik serta kemampuan cor yang baik, paduan aluminium - silikon hipereutektik telah menjadi suatu kandidat material untuk aplikasi - aplikasi yang membutuhkan sifat mekanis yang baik seperti piston.Walaupun demikian, paduan ini memiliki kekurangan yaitu paduan akan semakin bertambah brittle seiring dengan bertambahnya kandungan silicon dikarenakan oleh adanya silikon primer yang kasar. Terdapat berbagai cara untuk meminimalkan ukuran dari fasa silikon salah satunya adalah modifikasi dengan penambahan modifier.Pada penelitian ini, material AC8A didesain pada kondisi hipereutektik. Modifier fosfor ditambahkan dengan komposisi 0,0025 wt%, 0,0027 wt %, 0,0038 wt %, 0,0046 wt % dan 0,0061 wt % P. Untuk mengetahui sifat mekanis material, dilakukan pengujian kekuatan tarik, kekerasan serta keausan. Pengujian struktur mikro, SEM dan EDAX dilakukan untuk mengetahu perubahan struktur mikro serta fasa - fasa yang terbentuk dalam paduan.Hasil penelitian menunjukkan bahwa penambahan fosfor pada material AC8A hipereutektik akan mengubah morfologi dan ukuran silikon primer dari yang berbentuk poligonal dan kasar menjadi berbentuk blocky dan halus. Silikon eutektik juga mengalami perubahan karena pertumbuhannya yang berasal dari ujung silikon primer dan dipengaruhi oleh morfologi dan ukuran silikon prime. Silikon eutektik berubah dari jarum - jarum halus yang panjang menjadi batangan pendek dan seperti titik dengan panjang rata - rata yang lebih pendek.Hasil pengujian kekerasan menunjukkan, dengan bertambahnya kadar fosfor (0,0025 wt%, 0,0027 wt %, 0,0038 wt %, 0,0046 wt % dan 0,0061 wt %), kekerasan akan meningkat dari 38 HRB menjadi 39 HRB,40 HRB, 41 HRB dan 42 HRB. Peningkatan juga terjadi pada nilai ketahanan aus material. Sedangkan nilai kekuatan tarik tidak menunjukkan kecenderungan tertentu dikarenakan terdapatnya porositas pada sampel.

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Because of the interesting properties such as high wear resistance, low thermal expansion coefficient, high resistance to corrosion and castability, hypereutectic Al-Si alloys have become a candidate material for potential applications including piston. Nevertheless, it has a disadvantage which is it becomes more brittle as the ratio of silicon is added because of the presence of coarse primary silicon. There are a lot of ways to minimize silicon phases, one of them is modification using modifier.

In this research, aluminium alloy desaigned as AC8A was desaigned in hypereutectic condition. Phosphorus modifier was added to the melt with composition 0,0025 wt%, 0,0027 wt %, 0,0038 wt %, 0,0046 wt % dan 0,0061 wt % P. Tensile strength, hardness and wear were tested in order to know mechanical properties of material. Microstructure testing, SEM and EDAX were conducted to observe microstructure changing and phases formed in alloy.

Results of this research show that phosphorus addition in hypereutectic AC8A alloy changes the morphology and size of primary silicon from coarse polygonal to fine blocky structure. Eutectic silicon is also changed because it grows from the tip of angles on the primary silicon and is influenced by the morphology and size of primary silicon. The eutectic silicon changes from long fine needle-like shape to short bars and dots with less average length.

Hardness testing shows that by increasing phosphorus addition (0 wt %, 0,003 wt%, 0,004 wt% , 0,005 wt% dan 0,006 wt%) to the melt, hardness of the material increases from 38 HRB to 39 HRB, 40 HRB, 41 HRB, and 42 HRB. Furthermore, the value of wear resistance also increases. Nevertheless, tensile strength doesn't show any tendency because of porosity."

"Pada umumnya modifier stronsium ditambahkan pada paduan Al-Si hipoeutektik dengan kadar Si < 12 %. Penambahan modifier stronsium pada paduan Al-Si hipoeutektik terbukti efektif meningkatkan sifat-sifat mekanis paduan. Sedangkan penambahan modifier stronsium pada paduan aluminium hipereutektik belum banyak dilakukan. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan modifier stronsium terhadap sifat mekanis paduan Al-Si hipereutektik (Si>12,7%). Sifat mekanis yang ingin diketahui setelah penambahan modifier stronsium adalah kekerasan, kekuatan tarik dan keausan. Dalam penelitian ini digunakan material AC8A dengan standar kadar Si sebesar 11-13%. Ditambahkan kristal silikon murni ke dalam material AC8A untuk mendapatkan kondisi hipereutektik (Si>12.7%). Perbedaan penambahan kadar stronsium dalam paduan AC8A hipereutektik merupakan variabel dalam penelitian ini, sedangkan kondisi-kondisi proses lainnya dibuat sama. Stronsium yang ditambahkan adalah sebesar 0% wt, 0.126% wt, 0.208% wt, 0.284% wt dan 0.299% wt.Hasil penelitian menunjukkan bahwa dengan penambahan modifier stronsium pada paduan AC8A hipereutektik akan mengubah bentuk silicon eutektik dari acircular menjadi fibrous dan fasa intermetalik yang terbentuk menjadi lebih tersebar. Selain itu silikon primer akan ditekan pertumbuhannya sehingga berukuran lebih kecil dan lebih tersebar merata. Hasil pengujian kekerasan dan keausan menunjukkan adanya kekerasan dan ketahanan aus yang cenderung meningkat dengan peningkatan kadar stronsium yang ditambahkan. Kekerasan cenderung meningkat secara berturut-turut dari 41 HRB menjadi 44 HRB, 45 HRB, 43 HRB dan 48 HRB. Ketahanan aus meningkat dengan laju aus yang cenderung semakin menurun secara berturut-turut dari 3.27 x 10^-5 mm3/mm menjadi 2.01 x 10^-5 mm3/mm, 1.82 x 10^-5 mm3/mm, 2.27 x 10^-5 mm3/mm, dan 1.28 x 10^-5 mm3/mm. Kekuatan tarik yang didapatkan berturut-turut dari 173 Mpa menjadi 187 Mpa, 168 Mpa, 172 Mpa dan 185 Mpa. Nilai elongasi cenderung mengalami penurunan yaitu dari 0.125 menjadi 0.123, 0.118, 0.124 dan 0.114.

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In general, stronsium modifier is added to hypoeutectic Al-Si alloys with Si content < 12%. Addition of stronsium modifier in hypoeutectic Al-Si alloys effectivelly improve mechanical properties of alloys. Whereas, addition of stronsium modifier in hypereutectic Al-Si alloys is done rarely. This research has purpose to know effect of stronsium modifier addition on mechanical properties of hypereutectic Al-Si alloys. The mechanical properties that will be observed in this research are hardness, tensile strength and wear resistant. This research use AC8A material with 11-13% standard of Si content. Silicon crystal is added to AC8A material for obtaining hypereutectic condition (Si >12.7%). The difference of amount stronsium addition is as variable on this research. The other condition casting process, such as : strontium modifier addition temperature, cast temperature, solidification time and casting time are the same. The amount of strontium modifier which added is 0,126% wt, 0.208% wt, 0.284% wt and 0.299% wt.

The result of research show that with addition of strontium modifier to hypereutectic AC8A alloy will change eutectic silicon morphology from acircular to fibrous and intermetallic phase that be formed become more uniformly dispersed. Another, the growth of primary silicon will be suppressed until finer in size and more uniformly dispersed. The results both of hardness and wear testing show presence of disposed increasing in hardness and wear resistant with rising of Sr content that be added. The hardness disposed increase, in succession, from 41 HRB to 44 HRB, 45 HRB, 43 HRB and 48 HRB. Wear resistant disposed increase with disposed decreasing of wear rate, in succession, from 3.27 x 10-5 mm3/mm to 2.01 x 10^-5 mm3/mm, 1.82 x 10^-5 mm3/mm, 2.27 x 10^-5 mm3/mm, and 1.28 x 10^-5 mm3/mm. Tensile strength that be obtained, in succession, from 173 Mpa to 187 Mpa, 168 Mpa, 172 Mpa and 185 Mpa. The value of elongation disposed decrease from 0.125 to 0.123, 0.118, 0.124 and 0.114."

"Aluminum matrix composite (AMC) menjadi material yang sangat potensial bagi aplikasi industri ketika terdapat kebutuhan untuk mendapatkan kombinasi sifat ringan dengan sifat lainnya yang menunjang seperti kekuatan, kekakuan, ketahanan aus, konduktivitas listrik dan termal tinggi, dan koefisien ekspansi termal rendah. Namun material AMC sangat rentan terkena korosi pitting dan galvanik, yang disebabkan oleh pembentukan pasangan galvanik antara matriks dan penguat, serta terbentuknya mikrostruktur pada interface penguat/matrix. Anodisasi merupakan proses modifikasi permukaan yang potensial untuk meningkatkan ketahanan korosi AMC dengan menghasilkan lapisan oksida berpori. Namun, adanya penguat dalam AMC menghalangi pembentukan lapisan oksida protektif dengan mendorong terbentuknya cavity dan retak mikro. Oleh karena itu, metode cerium sealing digunakan untuk memperbaiki cacat pada lapisan oksida hasil anodisasi, sehingga dapat meningkatkan ketahanan korosi pada lingkungan yang sangat agresif.Penelitian ini bertujuan untuk menganalisis pengaruh parameter proses yakni temperatur dan rapat arus anodisasi terhadap pembentukan lapisan anodik berpori. Anodisasi dilakukan pada tiga temperatur yakni 25°C,0°C dan -25°C dengan variasi rapat arus 25,20 dan 15 mA/cm2. Pengujian kekerasan mikro Vickers digunakan untuk mengetahui sifat mekanik lapisan anodik. Pengamatan struktur mikro menggunakan FE-SEM untuk mengetahui morfologi permukaan dan mengukur ketebalan lapisan anodik.Hasil pengujian menunjukkan penurunan temperatur dan rapat arus akan meningkatkan kekerasan permukaan lapisan anodik alumina dimana kekerasan tertinggi adalah 427 HV yang didapat pada temperatur -25°C dengan rapat arus 15mA/cm2. Penurunan temperatur dan rapat arus juga relatif akan meningkatkan kerapatan dan keseragaman permukaan hasil anodisasi. Serta penurunan temperatur hingga 0°C akan meningkatkan ketebalan lapisan oksida dimana ketebalan terbesar adalah 14,13 μm yang yang didapat pada temperatur 0°C dengan rapat arus 25mA/cm2. Namun ketebalan kembali menurun pada saat diturunkan ke temperatur -25°C.

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Aluminum matrix composites (AMC) become potential materials for transport application where there is an obvious need for combination of weight saving and other properties, i.e. high specific strength, high specific stiffness, electrical and thermal conductivities, low coefficient of thermal expansion and wear resistance. However they are generally susceptible to corrosion in various environments, due to galvanic reactions between the reinforcements and the matrix, and selective corrosion on the interface due to the formation of new compounds. Anodizing has been considered as a potential modification treatment for enhancing corrosion resistant of AMC by forming porous anodic oxide on the surface area.

This study aims to analyze the influence of anodizing process parameters which is temperature and current density on the formation of porous anodic coating, Anodizing process has been done at three different temperatures which are 25°C,0°C and -25°C with variation of current density at 25,20 and 15 mA/cm2. Vickers microhardness testing was used to determine the mechanical properties of anodic layer. Observation of microstructure using FE-SEM to determine surface morphology and to measure anodic layer thickness.

Test results showed that decreasing temperature and current density would increase surface hardness of aluminium anodic layer. The highest surface hardness was 427 HV which was got by anodizing at temperature -25°C with using 15 mA/cm2 of current density. Decreasing temperature and current density would also relatively increasing density and make the surface smoother and looks more uniform. Decreasing temperature until 0°C would increase thickness of the oxide layer where the highest thickness was 14,13 μm which was got by anodizing at temperature 0°C with using 25 mA/cm2 of current density. But the thickness would decrease when the temperature was decreased to -25°C."

"Penelitian tentang pengaruh penambahan cover flux berbahan utama garam lokal terhadap porositas dan sifat mekanik pada peleburan paduan aluminium AC3A telah terlaksana dengan baik. Pada penelitian ini pembuatan fluks dengan memanfaatkan garam yang berasal dari dalam negeri dengan bahan – bahan pendukung lainnya yaitu natrium sulfat, natrium nitrat, dan natrium silikofluorida. Tahapan pembuatan cover flux meliputi pengayakan, pencampuran, pemanasan, pengeringan, dan pengayakan kedua. Karakterisasi SEM, EDS, DSC, Pengujian Berat Jenis, dan XRD dilakukan pada sampel cover flux yang sudah dibuat menunjukan proses dan produk yang dihasilkan menunjukan reaksi yang efektif dan dapat diaplikasikan pada peleburan aluminium. Kemudian sampel cover flux yang sudah dibuat ditambahkan dalam peleburan aluminium AC3A, setelah itu dilakukan karakterisasi hasil peleburannya. Karakterisasi OES menunjukan tipe aluminium yang digunakan untuk penelitian adalah Aluminium AC3A. Setelah itu dilakukan pengujian fluiditas dengan mesin PoDFA yang menunjukan bahwa fluiditas aluminium cair setelah ditambahkan cover flux menunjukan hasil yang lebih baik. Pengujian porositas dilakukan dengan OSTEK Porosity Tester menunjukan setelah penambahan persentase porositas pada hasil peleburan menurun. Pengujian tarik dan impak yang dilakukan menunjukan produk peleburan aluminium setelah ditambahkan cover flux memiliki sifat mekanik yang lebih baik dibanding yang tidak ditambahkan.

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Research on the effect of adding a cover flux made from local salt to the porosity and mechanical properties of the AC3A aluminum alloy smelting has been carried out well. In this study, flux was made by utilizing domestically sourced salt with other supporting materials, such as sodium sulfate, sodium nitrate, and sodium silicon fluoride. The stages of making cover flux include sieving, mixing, heating, drying, and second sieving. Characterization of SEM, EDS, DSC, Specific Gravity Testing, and XRD were carried out on the cover flux samples that had been made, showing the processes and products that produced an effective reaction and could be applied to aluminum casting. Then the cover flux sample that has been added to the AC3A aluminum casting, after that characterization of the smelting results is carried out. OES characterization shows the type of aluminum used for research is Aluminum AC3A. After that, testing the fluidity with the PoDFA machine, it shows that the fluidity of aluminum after adding cover flux shows better results. Porosity testing was carried out with the OSTEK Porosity Tester, which showed a decrease of porosity percentage in the AC3A casting results. Tensile and impact tests showed that the aluminum product after the addition of cover flux had better mechanical properties than those that were not added."