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All Journal Journal of Renewable Energy and Mechanics Metalurgi
Akhmad Ardian Korda, Akhmad Ardian
Bandung Institute of Technology
Automotive Engineering Engineering Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering Social Sciences

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Microstructural Stability and High-Temperature Oxidation Behavior of Al0.25CoCrCuFeNi High Entropy Alloy Muhammad, Fadhli; Lestari, Ernyta Mei; Achmad, Tria Laksana; Korda, Akhmad Ardian; Prawara, Budi; Prajitno, Djoko Hadi; Jihad, Bagus Hayatul; Setianto, Muhamad Hananuputra; Basuki, Eddy Agus
Metalurgi Vol 39, No 1 (2024): Metalurgi Vol. 39 No. 1 2024
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/metalurgi.2024.745

Abstract

Al0.25CoCrCuFeNi is a high-entropy alloy composed of transition metals, specifically designed for high-temperature applications owing to its favorable mechanical properties, high melting point, and excellent high-temperature resistance. This alloy has been identified as a promising material for space exploration, particularly in the fabrication of combustion chambers and rocket nozzles by the National Aeronautics and Space Agency. Ongoing alloy development involves modifying the elemental composition. This study reduced aluminum content in the equiatomic AlCoCrCuFeNi alloy to Al0.25CoCrCuFeNi, followed by isothermal oxidation treatments at 800, 900, and 1000℃. A series of experiments were conducted to investigate the microstructure stability and oxidation behavior of the Al0.25CoCrCuFeNi alloy. The alloying elements were melted using a single DC electric arc furnace, followed by homogenization at 1100°C for 10 hours in an inert atmosphere. Subsequently, samples were cut into coupons for isothermal oxidation testing at the desired temperatures for 2, 16, 40, and 168 hours. The oxidized samples were characterized using XRD (x-ray diffraction), SEM (scanning electron microscopy) equipped with EDS (energy-dispersive X-ray spectroscopy), optical microscopy, and Vickers hardness testing. The as-homogenized alloy consisted of two constituent phases: an FCC (face-centered cubic) phase in the dendritic region and a copper-rich FCC phase in the inter-dendritic region. The oxides formed during the oxidation process included Al2O3, Cr2O3, Fe3O4, CoO, CuO, NiO, and spinel oxides (Co,Ni,Cu)(Al,Cr,Fe)2O4), with distinct formation mechanisms at each temperature.
Effect of Quenching Medium and Tempering Temperature on Microstructure and Hardness of JIS SUP 9 Steel: Pengaruh Media Pendingin dan Temperatur Tempering pada Mikrostruktur dan Kekerasan Baja JIS SUP 9 Harmaji, Andrie; Korda, Akhmad Ardian; Ramadhan, Rama; Pambudi, Satrio
Journal of Renewable Energy and Mechanics Vol. 6 No. 01 (2023): REM VOL 6 NO 01 2023
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25299/rem.2023.10973

Abstract

JIS SUP 9 steel is one of the materials commonly used for suspension components in motorized vehicles with medium carbon steel base material. It must have good hardness and toughness so that failure does not occur during operational. This research was conducted to increase the hardness of JIS SUP 9 Steel through a heat treatment and various quenching media. The heat treatment was carried out with 830-880ºC temperature with a holding time of 7 minutes then cooled using water and oil. After treatment, tempering was carried out with a holding time of 7 minutes and then cooled in room temperature. Hardness testing was carried out using Microhardness Vickers and then the microstructure was observed using an Olympus Metallurgical Microscope. The results show that heat treatment followed by rapid cooling increases the initial hardness of JIS SUP 9 (229 VHN) steel. The decrease in hardness after the tempering process will be higher with increasing tempering temperature. The results of the microstructure of the sample without heat treatment showed pearlite and ferrite phases. After heat treatment, tempered martensite, residual austenite and carbide phases appear. It can be concluded that changes in the microstructure affect the hardness of JIS SUP 9 steel.
Co-Authors Achmad, Tria Laksana Basuki, Eddy Agus Budi Prawara Djoko Hadi Prajitno Fadhli Muhammad Harmaji, Andrie Jihad, Bagus Hayatul Lestari, Ernyta Mei Pambudi, Satrio Ramadhan, Rama Rizky Hidayat, Rizky Setiadi Suriana, Setiadi Setianto, Muhamad Hananuputra