ISOTHERMAL OXIDATION BEHAVIOR OF AL0.25COCRFENI HIGH ENTROPY ALLOY AT 900, 1000, AND 11000C TEMPERATURE

• Main Author: L. S. L. Sitorus, Ronald
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/74906
• Institution: Institut Teknologi Bandung

the production of metal alloys for use at high temperatures. The latest generation of material development in the last two decades has led to the design of high entropy-based metal alloys. High entropy metal alloys have better oxidation, corrosion and high temperature resistance when compared to conventional metal alloys and super metal alloys. For applications at high temperatures, some of the elements often used are Al, Cr, and Si, because the oxides formed are protective, namely by forming Al2O3, Cr2O3, or SiO2. To determine the rate of oxide formation in metals, several measurements can be made both on the amount of metal consumed, the amount of oxygen consumed, and the amount of oxygen used during the reaction. At high temperatures, there are three commonly used oxidation reaction kinetics models, namely linear, parabolic, and logarithmic rate kinetics. Generally, in isothermal oxidation, the rate kinetics follow a parabolic equation, meaning that the longer the oxidation is carried out, the less the thickness of the oxide scale formed. In this study, the test temperatures were 900, 1000, and 11000C, with a variation of test time for 2, 16, 40 hours, and 7 day under 11000C with a sample of Al0.25CoCrFeNi high entropy alloy. Based on the experimental results, it is known that in the Al0.25CoCrFeNi sample, the oxides that first formed at 9000C-2 hours were spinel of NiFe2O4 and CoFe2O4. Then, as time passes, the protective oxide Cr2O3 begins to form by diffusion of ions through the pre-formed oxide scale, while at high temperatures and very long times, another protective oxide Al2O3 is formed. It is also known that the higher the temperature and the longer the oxidation time, the more Cr2O3 oxide will be formed. Based on the plotting results of oxidation rate kinetics, it is known that at a Temperatur of 9000C Al0.25CoCrFeNi has the best oxidation resistance, with the oxide formation rate equation is x2= 9 x 10-7t + 7 x 10-5, with the value of activation energy is 54.7467kJ/mol