EFFECT OF CU CONCENTRATION VARIATION ON MECHANICAL PROPERTIES OF FENICRCOCU HIGH ENTROPY ALLOY WITH MOLECULAR DYNAMICS SIMULATION

• Main Author: Fahira Ritonga, Ghanyyah
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/82699
• Institution: Institut Teknologi Bandung

FeNiCrCoCu alloy is a high entropy alloy with radiation, creep, creep-fatigue, corrosion resistance, high strength and ductility. This alloy can potentially be a candidate material for nuclear reactor applications due to its superior mechanical properties of high resistance to irradiation damage and resistance to extreme conditions such as temperature, stress, corrosive environments, and high heat flux. FeNiCrCoCu alloys were chosen because they have good phase stability and experience only minor structural changes when irradiated compared to alloys for other nuclear reactor applications. Studying the behavior and mechanical properties of alloys through experiments requires time and money and it isn't easy to create a mathematical model of the optimal alloy concentration ratio, so simulation using a more efficient molecular dynamics method is needed. Molecular dynamics simulation of FeNiCrCoCu alloy using large-scale atomic/molecular massively parallel simulator (LAMMPS) has been conducted to study the effect of Cu concentration variation in the concentration range of 0-30 at% and at room temperature (300 K) on lattice parameters, ultimate tensile strength (UTS), elastic modulus, yield strength, and stacking fault energy (SFE). The simulation begins with structural optimization to obtain equilibrium lattice parameter values, followed by uniaxial tensile tests and calculation of SFE values. In addition, microstructure evolution analysis using common neighbor analysis (CNA) and dislocation behavior in the alloy with dislocation analysis (DXA) were also conducted to explain the effect of Cu addition on the mechanical properties of the alloy. The simulation results show that increasing the Cu concentration will decrease the value of the alloy's lattice parameters. The lattice parameter value of medium entropy alloy (MEA) FeNiCrCo is 3.554 Å and high entropy alloy (HEA) FeNiCrCoCu equiatomic is 3.552 Å. Increasing Cu concentration decreases the alloy's UTS value but increases the elastic modulus and yield strength. The UTS values of FeNiCrCo MEA and FeNiCrCoCu equiatomic HEA are 14.6 GPa and 13.6 GPa, respectively, while their elastic moduli are 206.7 GPa and 224.6 GPa, and their yield strengths are 8.8 GPa and 8.5 GPa. The SFE value of FeNiCrCo MEA is 65.6 mJ/m2 while the SFE value of equiatomic FeNiCrCoCu HEA is 63.2 mJ/m2. The SFE value tends to decrease with the addition of Cu concentration. Based on CNA and DXA analysis, equiatomic FeNiCrCoCu HEA undergoes structural changes from FCC to HCP and faster formation of Shockley partial dislocations than FeNiCrCo MEA.