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"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."

"Riset ini menerangkan suatu investigasi tentang perilaku liquid metal embrittlement (LME) pada aluminium paduan 6061-T6-Alclad. Tujuan riset ini adalah mempelajari pengaruh cairan NaK pada perilaku perambatan retak aluminium paduan dengan menggunakan sistem yang telah dikembangkan sebelumnya untuk mengukur laju perambatan retak (da/dt) sebagai suatu fungsi konsentrasi tegangan (K) dan untuk menentukan respon da/dt vs K pada beberapa faktor yang mempengaruhi penggetasan. Kebanyakan informasi yang ada pada LME yang ada telah diperoleh dari hasil-hasil pengujian ketangguhan perpatahan (fi-acture toughness) pada logam padat yang dibasahi oleh logam cair. Pada riset ini, pengujian ketangguhan perpatahan aluminium paduan yang dibasahi dengan cairan NaK dilakukan dengan dengan beberapa laju crack mouth opening displacement (CMOD), dan lama penuaan lebih (averaging time) pada spesimen DCB (double cantilever beam) beralur dan tak beralur. Dari hasil pengujian diketahui bahwa kehadiran logam cair NaK pada pangkal retak sangat mempengaruhi ketangguhan perpatahan material aluminium 6061-T6-Alclad, yang mana nilai intensitas tegangan ambang turun dari 35 MPa.m^1/2 menjadi 8 MPa.m^1/2. Juga diketahui bahwa averaging cukup signifikan mempengaruhi karakterisasi da/dt vs K, tetapi pengaruh alur pada spesimen tidak begitu signifikan.

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This work describes an investigation of the liquid metal embrittlement (LME) behavior of aluminium alloy 6061-T6 Alclad embrittled by liquid sodium-potassium (NaK). The aims are to study the effect of liquid NaK on crack propagation behavior in aluminium alloy using a system previously developed to measure the crack speed (da/dt) as a function of stress intensity (K) and to determine da/dt vs K response at the investigated material in some factors influencing embrittlement.

Most of the information available on LME at present has been deduced from the results of, fracture toughness tests of the solid metal wetted by a liquid metal. In this study, fracture toughness tests of the aluminium alloy wetted by liquid NaK have been carried out over a range the crack mouth opening displacement (CMOD), and over aging time, and also grooved and ungrooved.

DCB specimens were studied. It was found that the presence of liquid NaK in the crack tip has severe affected the fracture toughness of aluminium alloy 6061-T6-Alclad which the value of threshold stress intensity drop from 35 MPa.m^1/2 to 8 MPa.m^1/2. Others, the effects of averaging time were significant but the of effect groove and CMOD rate did not significantly affect the da/dt vs K characterisation."

"ABSTRAKPaduan AlZrCe dengan komposisi 0.12%wt Zr dan 0,15%wt Cediperkuat dengan partikel nano Al2O3 dari 0.5%Vf hingga 2,0%Vf. Peningkatan keterbasahan partikel Al2O3 pada matrik AlZrCe dilakukan dengan penambahan magnesium. Komposit dikarakterisasi terhadap sifat mekanik, listrik dan termal.Titik optimun dari empat jenis matrik AlZrCe, AlZrCe-2%Mg, AlZrCe-3%Mg, dan AlZrCe-5%Mg terjadi pada rentang 1%Vf hingga 1,2%Vf Al2O3. Kekuatan tarik maksimun 204 MPa terjadi pada 1,2%Vf Al2O3 dengan kadar 5%wt Mg. Efek partikel penguat terhadap penurunan konduktivitas listrik tidak terlalu besar tetapi sebaliknya dengan penambahan 2%wt, 3%wt dan 5%wt Mg menyebabkan penurunan konduktivitas listrik hingga lebih dari 8% IACS yaitu dari 59% IACS untuk komposit tanpa Mg menjadi 52% IACS, 49% IACS dan 45% IACS berturut-turut. Demikian pula sifat ekspansi termal komposit turun dengan penambahan partikel penguat. Penambahan partikel pada aluminium Al2O3 dapat menghaluskan butir sehingga diperoleh ukuran butir yang lebih halus pada fraksi volume 1.0% dan 1,2%. Proses canai dingin dilakukan dengan reduksi 33%, 56% dan 78%yang menghasilkan peningkatan sifat mekanik dan listrik yang maksimumpada pada reduksi 78%.Komposit AlZrCe/1%Vf.Al2O3 reduksi 78% (282MPa, 62,4% IACS) dapat mengungguli kabel konduktor listrik yang telah digunakan dalam transmisi listrik seperti Stabiloy (Al-0.5Fe-0.22Cu) dengan sifat tarik dan listrik yaitu 114MPa dan 61,8% IACS.

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ABSTRACT

AlZrCe alloy with a 0.12% wt 0.15 wt% Zr and Ce reinforced with fraction volum of nano particles Al2O3 from 0.5% to 2.0%. Improved wettability of Al2O3 particles in the matrix AlZrCe done with the addition of magnesium. Composites were characterized for mechanical properties, electrical and thermal. Optimum point of the four types of matrices AlZrCe, AlZrCe-2% Mg, AlZrCe-3% Mg, and AlZrCe-5% Mg occurs in the range of 1% to 1.2% VfAl2O3. Maximum tensile strength of 204 MPa occurred in 1.2 %VfAl2O3with levels of 5%wt Mg. Increasing %Vf particle decrease the electrical conductivity is not significant but instead with the addition of 2 wt%, 3 wt% and 5 wt% Mg causes a decrease in electrical conductivity by more than 8% IACS ie from 59% IACS to the composite without Mg to 52% IACS, 49% IACS and 45% IACS respectively. Similarly, the thermal expansion properties of the composite decrease with the addition of reinforced particles. The addition of Al2O3 particles in aluminum can refine the grain in order to obtain a finer grain size on the volume fraction of 1.0% and 1.2%. Cold rolled process carried out by reduction of 33%, 56% and 78%, which results in improved mechanical and electrical properties at the maximum reduction of 78%. Composite AlZrCe/1%Vf.Al2O3with reduction of 78% (282MPa, 62.4% IACS) may exceed the properties of the electrical conductor wires that have been used in power transmission such as Stabiloy (Al-0.5Fe-0.22Cu) whichhas tensile and electricity properties are 114MPa and 61.8% IACS."