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"Effect of Ni content on the hardness, corrosion rate and heat stability of cladding structure material with an alminium base alloy. The development of cladding structure material with an aluminium base alloy was performed by variation of Ni content in the alloy. Various of Ni content in alloy will generates material properties changes in mechanical, physical, and thermal. The investigation and development of cladding structure material was studied order to to get materials which have good mechanical properties and corrosion resistance. The examination of the hardness of -eNi structure materials was observed using vickers method..."

"Aluminium alloys are developed as airplane body due to their lighter weight compared to steel and good formability. Aluminium 7XXX series with Zn and Mg alloying elements is commonly used because its mechanical properties can be improved through a deformation process. A deformation process such as cold rolling may increase the hardness of an alloy through strain hardening. An annealing process following the deformation process will recover ductility through stress relief, recrystallization, and grain growth mechanisms. This research aimed to discover the effect of cold rolling and annealing temperature on the recrystallization and mechanical properties of Al-4.7Zn-1.8Mg (wt. %) alloy. The alloy was produced by a squeeze casting process. Homogenization was conducted at 400oC for 4 hours followed by cold rolling with degrees of deformation of 5%, 10%, and 20%. The samples with 20% deformation were then annealed at 300oC, 400oC, and 500oC for 2 h. The Vickers hardness test was performed on the cold-rolled and annealed samples to reveal the strain hardening effect and subsequent recrystallization process. The microstructure was observed using an optical microscope and a Scanning Electron Microscope (SEM). The results showed that the higher the deformation, the more elongated the grains. Deformation of 5, 10 and 20% led to grain shape ratios of 2.19, 3.19 and 4.59, respectively and increase in the hardness of the alloy from 69.5 VHN to 95.3, 100.1 and 105.4 VHN, respectively. Slip bands and cross slips were found only in the 20% deformed samples. The annealing process resulted in recovery at 300oC, followed by recrystallization at 400oC (dgrain ~290 ?m) and grain growth at 500oC (dgrain ~434 ?m). Annealing temperatures of 300oC, 400oC and 500oC decreased the hardness of the alloy from 105.4 VHN to 71.5, 96.8 and 95.3 VHN, respectively."

"Komposit aluminium A356/nano SiC dapat menjadi material alternatif blok rem kereta dikarenakan sifatnya yang ringan, ulet, dan dapat ditingkatkan sifat mekanisnya. Pada penelitian ini digunakan variasi penambahan %Vf nano SiC sebesar 0.05%, 0.10%, 0.15%, 0.20%, dan 0.25% ke dalam matriks aluminium A356, serta dilakukan penambahan modifier Sr 0.046 wt% dan Mg 2 wt%.Hasil dari penelitian didapatkan peningkatan kekuatan yang optimum sebesar 175.45 MPa dengan elongasi sebesar 7.914% pada penambahan nano SiC 0.10 %Vf. Ketahanan aus juga meningkat seiring dengan peningkatan kekerasan komposit A356/nano SiC. Sedangkan kekuatan impak hanya berkurang sedikit akibat penambahan %Vf nano SiC. Peningkatan kekuatan mekanis terjadi akibat terbentuknya fasa MgAl2O4 pada antarmuka partikel nano SiC dan matriks Al A356 dan persentase porositas yang kecil. Penambahan modifier Sr menyebabkan fasa Si eutektik yang terbentuk menjadi halus.

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A356/nano SiC composite is an alternative material as train?s brake shoe because of its light weight, ductility, and the ability to improve its mechanical properties. In this work, the casting is done via stir casting method by various additions of 0.05%, 0.10%, 0.15%, 0.20%, and 0.25% volume fraction. Small amounts of Sr (0.046 wt%) and 2 wt% of Mg are also added into A356 matrix.

The results show the optimum UTS reach 175.45 MPa with elongation of 7.914% at addition of 0.10 %Vf nano SiC. The wear resistance of this composite also increase as the hardness increases as increasing of addition of nano SiC particle. Meanwhile, the impact strength just slightly decreases as the increasing of nano SiC addition. The improvement of mechanical properties of A356/nano SiC composite is contributed by formation of thin layer MgAl2O4 surrounding the nano SiC particles and low percentage of porosity. The addition of Sr caused the morphology of eutectic Si in the microstructure fine and fibrous."

"Pengaruh unsur logam tanah jarang samarium terhadap paduan Al-5Zn-0.5Cu diteliti dengan pengamatan Optical Microscope OM dan Scanning Electron Microscope/Energy Dispersive Spectroscopy SEM/EDS serta pengujian Differential Scanning Calorimetry DSC dan Polarisasi Siklik. Kadar samarium yang diteliti adalah 0wt , 0.1wt , 0.3wt dan 0.5wt. Pengamatan OM dilakukan untuk melihat perubahan ukuran butir dan letak presipitat terbentuk. SEM/EDS dilakukan untuk mengetahui morfologi dari presipitat yang terbentuk dan identifikasi unsur-unsur yang ada pada permukaan. DSC dilakukan untuk mengetahui proses transformasi fasa dan proses solidifikasi fasa intermetalik. Polarisasi siklik dilakukan untuk mengetahui perilaku korosi anoda korban Al-5Zn-0.5Cu-xSm. Kehadiran unsur samarium membentuk presipitat pada batas butir yang membuat butir-butir pada mikrostruktur menjadi lebih halus. Presipitat yang terbentuk merusak lapisan pasif aluminium pada permukaan paduan dan mempercepat laju korosi dengan membuat paduan menjadi lebih anodik.

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The effect of addition of samarium rare earth on Al 5Zn 0.5Cu alloy was investigated with Differential Scanning Calorimetry DSC and Cyclic Polarization, complemented with Optical Microscope OM and Scanning Electron Microscope Energy Dispersive Spectroscopy SEM EDS observation. The content of samarium tested was 0wt, 0.1wt , 0.3wt and 0.5wt. Observation with OM was done to see the change of the grain size and the location of formed precipitates. SEM EDS was used to see the morphology of the formed precipitates and to identify elements present on the specimen surface.

DSC was used to know the phase transformation and solidification process of intermetallic phase. Cyclic polarization was used to know the corrosion characteristics of Al 5Zn 0.5Cu xSm. The presence of samarium formed precipitates on the grain boundary which made the grains on the microstructure finer. The formed precipitates impair the aluminium oxide film on the alloy surface and accelerate corrosion rate by making the alloy more anodic."

"Adanya perkembangan teknologi bahan, khususnya untuk aplikasi kabel penghantar listrik menyebabkan terjadinya pergeseran terhadap bahan yang digunakan untuk konduktor listrik yang sebelumnya menggunakan tembaga dan sekarang mulai digeser oleh paduan Aluminium. Pergeseran tersebut disebabkan oleh paduan aluminium mempunyai keunggulan dibandingkan dengan kawat tembaga antara lain; mempunyai berat jenis lebih rendah, proses pembuatan relatif lebih mudah, serta harga relatif lebih murah. Bahan konduktor tidak selalu berada pada lingkungan yang ideal. Isu pencemaran udara tidak luput dari kualitas bahan konduktor di lapangan, salah satu contohnya adalah hujan asam. Hujan asam dapat mempengaruhi kualitas bahan konduktor. Hujan asam dapat membuat korosi dan menurunkan konduktivitas. Penelitian ini bertujuan untuk mendapatkan penyebab menurunnya konduktivitas bahan konduktor aluminium dan paduan aluminium dengan melakukan pengujian konduktor yang terkontaminasi oleh larutan H2SO4. Bahan konduktor yang digunakan adalah aluminium murni, AlZrCe+Mg 1%+ Al2O31% dan AlZrCe + Al2O31%. Penelitian dilakukan dengan merendam bahan konduktor didalam larutan H2SO4 1%, 3%, dan 5% selama 7 hari dan data diambil pada hari pertama, kedua, ketiga dan ketujuh. Konduktivitas hari pertama dan ketujuh mengalami penurunan konduktivitas akibat larutnya butir butir aluminium dan paduan aluminium. kondisi awal konduktivitas aluminium murni IACS pada hari ketujuh atau 7x24 jam terjadi penurunan menjadi 57,584% IACS pada larutan 1%, 56,486% IACS pada larutan 3% dan 55,632% IACS pada larutan 5%. Hal ini dapat terjadi karena elektron bebas yang melewati kisi-kisi kristal yang terdistorsi, maka elektron-elektron akan dibelokkan sehingga jarak bebas rata-ratanya menurun atau tahanan listrik menjadi naik dan kisi kristal terdistorsi didapat dari paduan Aluminium

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The development of materials technology, especially for the application of electrically conductive wires causing a shift to materials used for electrical conductors previously using copper and are now starting to be shifted by Aluminum alloy. The shift is caused by aluminum alloys have advantages over copper wire, among others; lower specific gravity, easy manufacturing process, cheaper price. Conductor materials are not always at the ideal environment.

The issue of air pollution does not escape from the conductor material quality in the field, one example is acid rain. Acid rain can affect the quality of the conductor material. Acid rain can create corrosion and lowers conductivity. This study aimed to obtain the decrease in the conductivity of the conductor material of aluminum and aluminum alloy conductors by testing contaminated by H2SO4solution Conductor material used is pure aluminum, AlZrCe Mg + 1% + Al2O31% and AlZrCe + Al2O3 1%.

The study was conducted by immersing the conductor material in solution H2SO4 1%, 3%, and 5% for 7 days and the data taken on the first, second, third and seventh. The first day of the seventh conductivity and conductivity decreased due to the dissolution of the items to aluminum and aluminum alloys. Initial conditions IACS conductivity of pure aluminum on the seventh day or 7x24 hours decreased 57.584% IACS into a solution of 1%, 56.486% IACS in a solution of 3% and 55.632% IACS at a 5% solution. This may occur because the free electrons which pass through a crystal lattice that is distorted, then the electrons will be deflected so that the mean free path decreases or the electrical resistivity to be increased and distorted crystal lattice obtained from Aluminum alloy."