DESIGN OF HIGH ENTROPY ALLOYS COCRFENIMO AND COCRFENIW USING THERMODINAMICS CALCULATION AND FIRST PRINCIPLE SIMULATION FOR BIOMEDICAL APPLICATIONS

• Main Author: Fakhrozi, Azlan
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69268
• Institution: Institut Teknologi Bandung

Dependence on imported medical devices requires Indonesia to make industrial development and research in the field of medical devices a priority program. One of the metal alloy materials that has the potential to be used as a biomaterial for medical devices is high entropy alloy (HEA). HEA must meet the requirements to be used as high-quality biomaterials such as good mechanical properties, corrosion resistance, and biocompatibility. These properties can be achieved by careful alloy design including the selection of the right alloy composition. Conventional metal alloy design (trial and error) requires a lot of time and money. By computationally design various alloys with many compositions can be modeled easily so that the required mechanical properties of a particular application can be achieved with lower time and cost. In this study, the design of high-entropy alloys is modeled by calculating the value of stacking fault energy (SFE) with several variations in composition using thermodynamic calculation and first-principle methods. A series of simulations for calculating the SFE value of HEA have been carried out to study the effect of alloy composition and temperature on the SFE value and electronic structure. The thermodynamic calculation method was carried out at a temperature range of 0-1500 C.The first-principle was simulated at a temperature of 0 K to determine the equilibrium lattice parameters, structural equilibrium energy values, and the resulting electronic structure. From the simulation results, variations in alloy composition affect the SFE value of HEA. By using the thermodynamic calculation method on HEA CoCrFeNiMo and CoCrFeNiW, it was found that the addition of Co increased the SFE value within a certain range. The addition of Fe and Ni increased the SFE value significantly, while the addition of Cr, W and Mo decreased the SFE value. With the firstprinciple, the calculation of the SFE value by increasing the Fe and Ni concentrations and decreasing the W and Mo concentrations in both HEA resulted in an increase in the SFE value. By replacing W and Mo with Fe and Ni, it is also found that the charge accumulation zone decreases and increases the DOS value of the electronic structure of the alloy. To obtain the dominant deformation mechanism of the HEA alloy in the form of twinning, the concentration of Fe can be increased accompanied by reducing the concentration of W or Mo.