Atomic Scale Diffusion Study in Quaternary and Quinary Alloys of Co-Cr-Fe-Mn-Ni System

A chemically homogeneous structure models were established for the multi-principal alloy CoCrFeMnNi and the quaternary CrFeMnNi, CoFeMnNi, CoCrMnNi, CoCrFeNi, and CoCrFeMn alloys, and calculations were performed based on vacancy diffusion mechanism using lattice dynamics and molecular dynamics methods for the self-diffusion of each component atom. By calculating four thermodynamic parameters, namely, vacancy formation energy, atomic migration energy, formation entropy, and effective frequency at the transition state, the self-diffusion properties of each component atom were obtained. The formation energy, migration energy, and formation entropy of each component in different alloys were relatively close. The Arrhenius form of diffusion for each component in the quinary alloy showed that the results modified by experimental values using molecular dynamics were close to the measured values within a given temperature range. Directly substituting the thermodynamic parameters yielded results with some deviation from the measured values, with Mn and Cr exhibiting greater deviations. By substituting experimental values for formation energies, the result for Mn was close to the measured value, while the deviation of Cr data was still relatively large. This might be due to the error in the potential describing the formation energy and effective frequency. Calculating the thermodynamic parameters for quaternary alloys allowed the diffusion Arrhenius form to be obtained. The diffusion coefficient of Mn was much higher than that of other elements, while that of Cr was at a lower level, and the diffusion coefficients of Fe, Co, and Ni were close. In multi-principal alloy systems, there are interactions between the components that affect diffusion behavior, and the degree of influence varies depending on the component type. It seems that Co, Cr, and Mn tend to promote self-diffusion, while Fe and Ni tend to hinder diffusion in these alloys.

Automated summary

A chemically homogeneous structure models were established for different alloy compositions, and calculations were performed to investigate the self-diffusion properties of each component atom. The results showed that the diffusion properties of each component were relatively close in different alloys. The modified results using molecular dynamics were close to the measured values, while the direct substitution of thermodynamic parameters yielded some deviations. The diffusion coefficient of Mn was much higher than other elements in the quaternary alloys, while Cr had a lower diffusion coefficient. In multi-principal alloy systems, there were interactions between components that affected diffusion behavior, with Co, Cr, and Mn tending to promote self-diffusion and Fe and Ni tending to hinder diffusion.