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Bulk Metallic Glass (BMG) memiliki sifat mekanik, magnetik, kimia dan fisik yang berbeda dengan paduan polikristalin karena susunan internal atomnya yang tidak teratur. Sehingga, BMG memiliki kekuatan mekanik yang baik, kekerasan yang tinggi, ketahanan terhadap aus dan korosi yang tinggi, dan kehalusan permukaan yang baik. Berdasarkan sifat tersebut, BMG memiliki kelayakan yang menjanjikan di bidang industry. Dalam penelitian ini, metode pengecoran cetakan di tembaga digunakan untuk menyiapkan BMG paduan Cu45Zr45Al5Ag5. Paduan dileburkan ulang dengan pendinginan super cepat menggunakan mesin pendingin di bawah temperatur -25 oC. Dengan metode pengecoran cetakan di tembaga, sampel ukuran besar berbentuk batang dipotong dengan diameter 2 mm hingga 4 mm dan panjang 30 mm. Batang kemudian dipotong lagi menjadi spesimen berbentuk cakram. Untuk memastikan apakah sampel adalah BMG atau tidak, sampel dievaluasi dengan Scanning Electron Microscopy (SEM), Energy Dispersion Spectrometer (EDS), Differential Scanning Calorimetry (DSC), Electron Probe X-ray Micro Analyzer (EPMA), dan X -ray Difraction (XRD). Hasilnya dibahas dalam penelitian ini. Kata Kunci: Bulk Metallic Glasses, Cu45Zr45Al5Ag5, Pengecoran Cetakan di Tembaga.

Kalimantan has abundant natural resources, including wood. The physical properties of wood have varying strength and flexibility and could replace concrete reinforcement steel. In this study, the mechanical properties and sound insulation of one of Kalimantan's natural fiber combined with polyester matrix were investigated. Natural fibers used were teak wood (Tectona Grandis) with sawdust and wood chips. Specimens were made using the hand lay-up method with a wood volume fraction variable of 25%, 35%, and 50%. Afterward, the bending, morphology, and sound insulation tests were carried out. In this study, it can be concluded that the higher wood volume fraction used, the higher the ability of sound insulation. Conversely, it reduces the modulus of elasticity. Besides, the form of sawdust fillers has a better ability than wood chip fillers in terms of sound insulation and the modulus of elasticity.

This study aims to determine the effect of variations of the current with combining two welding techniques SMAW and FCAW in double v-groove against the hardness and microstructure of the dissimilar material of JIS G3101-SS400 and ASTM A36. JIS G3101 SS400 and ASTM A36 each with a thickness of 10 mm were used as the materials. The combination of SMAW welding with E7018 electrodes and FCAW with E71T-1 were used as the welding techniques. The current used in SMAW welding were 60 A, 75 A, and 90 A. While in FCAW welding the current used were 190 A, 205 A, and 220 A. Hardness and microstructure tests were carried out on each sample. The results of the study showed that the current in welding process affect the hardness value and microstructure of material. The higher the welding current, the value of hardness of the material going to decrease and vice versa. The highest hardness values in SMAW and FCAW welding are at currents of 60 A and 190 A. Then the current in the welding process also affect the microstructure produced in the weld and HAZ. The formed microstructure containing pearlite and ferrite. The higher welding current, the percentage of pearlite produced increase and the percentage of ferrite decrease.

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