DESIGN OF HIGH ENTROPY SUPERALLOY FENIALCRCO USING MOLECULAR DYNAMICS SIMULATION

• Main Author: Aisyana Wibowo, Putri
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/73136
• Institution: Institut Teknologi Bandung

FeNiAlCrCo alloy is a Fe-based high entropy superalloy used for applications at high temperatures due to its high strength and creep resistance. This alloy can be an alternative for the National Institute of Aeronautics and Space (LAPAN) to make nozzle rockets in their development of low earth orbit rockets. The nozzle on the rocket is in the exhaust system which has an aggressive environment with high pressure and temperature so that high strength and creep resistance is required at high temperatures. FeNiAlCrCo alloy was chosen because it has higher strength and lower price compared to Ni-based superalloy which is also one of the alloys for high temperature applications. Conventional metal alloy design will take a lot of time, cost, and effort, so a solution method is needed to simulate the effect of alloy composition to the mechanical properties. Design simulation of FeNiAlCrCo alloy has been carried out to study variations in the effect of alloy composition on lattice parameters, stacking fault energy (SFE) values, and ultimate compression strength (UCS) of the alloy using molecular dynamics (MD) simulations. In addition, the effect of lattice parameters on SFE and UCS values was also studied. MD simulation are carried out using the LAMMPS package with an FCC alloy structure and variations in the composition of Ni, Al, Cr, and Co are 11.75-16.25 at% and Fe is 35-39.5 at%. The simulation is carried out with a random distribution of atoms at 300 K. The simulation is started by optimizing the structure so that the equilibrium lattice parameter values were obtained, then continued with the uniaxial compression test, and the SFE value are calculated. From the simulation results, the lattice parameters of the equiatomic HEA FeNiAlCrCo is 3.626 Å and Fe35%NiAlCrCo HESA is 3.625 Å. The addition of Ni, Cr, and Co to the FeNiAlCrCo alloy will decrease the lattice parameters and the addition of Al to the alloy will increase the lattice parameters. The addition of Ni, Al, Cr, and Co to the FeNiAlCrCo alloy based on the simulation results will reduce the UCS value but their UCS values are still above the UCS value of the equiatomic HEA FeNiAlCrCo which is 11.26 GPa while the UCS value of HESA Fe35%NiAlCrCo is 12.56 GPa. The addition of Al, Cr, and Co to the FeNiAlCrCo alloy based on the simulation results will decrease the SFE value and the addition of Ni to the alloy will increase the SFE value. The SFE value for the equiatomic HEA FeNiAlCrCo is 4.22 mJ/m2 and the SFE value for HESA Fe35%NiAlCrCo is 27.28 mJ/m2.