EFFECT OF MN COMPOSITION ON THE MECHANICAL PROPERTIES OF HIGH ENTROPY ALLOY FENICRCOMN : MOLECULAR DYNAMICS STUDY

• Main Author: Purnaningtyas, Rahma
• Format: Final Project
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/82704
• Institution: Institut Teknologi Bandung

FeNiCrCoMn alloy commonly known as Cantor Alloy is a high entropy alloy that can be applied at a very low temperature (cryogenic) below -150 oC because it has good strength, ductility, and toughness. This alloy can be an alternative material for cryogenic tanks for liquid hydrogen storage. Cryogenic tanks require materials that have good mechanical properties and corrosion resistance. FeNiCrCoMn alloy was chosen as an alternative material for cryogenic tanks because of the higher fracture toughness compared to commonly used materials such as stainless steel, aluminum alloy, and nickel alloy. To study the mechanical properties of FeNiCrCoMn alloy, computational methods are used because it can save cost, time, and energy. Design simulations of FeNiCrCoMn alloys have been carried out to determine the effect of variations in Mn composition on the lattice parameters, ultimate tensile strength (UTS) values, elastic modulus, and stacking fault energy (SFE) values. In addition, this research also studied the phase changes and dislocation formation that occurred in the alloy. Molecular dynamics simulations were conducted using the LAMMPS program with single phase FCC structure and Mn composition variations in the range of 0 – 25 at%. Simulations were carried out at room temperature of 300 K and liquid hydrogen temperature of 20 K. The simulation begins with structural optimization so that equilibrium lattice parameters are obtained, then continues with uniaxial tensile and compression tests also calculation of SFE values. In addition, phase change analysis using CNA and dislocation analysis using DXA were also conducted to explain the effect of Mn on mechanical properties and SFE. Based on the simulation results, the lattice parameter value of FeNiCrCoMn equiatomic alloy is 3.595 Å and MEA FeNiCrCo alloy is 3.577 Å. The addition of Mn composition will increase the value of lattice parameters. The UTS value of FeNiCrCoMn equiatomic is 10.604 GPa and MEA FeNiCrCo alloy is 15.122 GPa. The addition of Mn composition tends to decrease the UTS value and the decrease in temperature increases the UTS value. The SFE value of FeNiCrCoMn alloy is very low at about -45 mJ/m2and the addition of Mn composition will tend to decrease the SFE value of the alloy. Based on CNA and DXA analysis, HEA FeNiCrCoMn alloy undergoes phase transformation from FCC to HCP faster and forms Shockley partial dislocation faster than MEA FeNiCrCo alloy.