Plastic behavior of a nanoporous high-entropy alloy under compression

Abstract

Nanoporous High-entropy alloys (HEA) have attracted increasing attention in recent years due to their remark-able mechanical properties and their capability as storage devices. However, chemical complexity involves fluctuations in the atomic environment, hindering the analysis of plasticity. Here, we perform molecular dynamics simulations of an equiatomic nanoporous single crystal FeCrNiCuCo HEA under compression to unveil the role of pores in the plastic behavior, including a random sample and a sample with short-range order. These results are compared to a nanoporous single crystal Average Atom (AA) sample with the same topology to assess the effect of chemical complexity. We find that the overall elastic and plastic regimes are similar in all samples, in contrast to previous reports for tensile tests. However, some differences can be distinguished between HEA samples and AA. Chemical complexity in the HEA favors dislocation nucleation and larger twinning activity, leading to a faster reduction of pores as reflected by the increase in relative density and decrease in surface-to-volume ratio. Following machine learning methods, linear vacancy clusters were found in all samples. These clusters exhibited a perfectly linear shape in AA and a less-defined shape in the HEA samples. Thus, our work provides new insights into the effect of chemical complexity and nanopores on the plasticity of HEAs under compression.

Nanoporous High-entropy alloys (HEA) have attracted increasing attention in recent years due to their remark-able mechanical properties and their capability as storage devices. However, chemical complexity involves fluctuations in the atomic environment, hindering the analysis of plasticity. Here, we perform molecular dynamics simulations of an equiatomic nanoporous single crystal FeCrNiCuCo HEA under compression to unveil the role of pores in the plastic behavior, including a random sample and a sample with short-range order. These results are compared to a nanoporous single crystal Average Atom (AA) sample with the same topology to assess the effect of chemical complexity. We find that the overall elastic and plastic regimes are similar in all samples, in contrast to previous reports for tensile tests. However, some differences can be distinguished between HEA samples and AA. Chemical complexity in the HEA favors dislocation nucleation and larger twinning activity, leading to a faster reduction of pores as reflected by the increase in relative density and decrease in surface-to-volume ratio. Following machine learning methods, linear vacancy clusters were found in all samples. These clusters exhibited a perfectly linear shape in AA and a less-defined shape in the HEA samples. Thus, our work provides new insights into the effect of chemical complexity and nanopores on the plasticity of HEAs under compression.