Microstructural evolution and mechanical properties of AlxCoCrFeNi high-entropy alloys under uniaxial tension: A molecular dynamics simulations study

• Published in: Materials today communications 2021-09, Vol.28, p.102525, Article 102525
• Main Authors: Jiang, Jun, Chen, Pengwan, Qiu, Jiali, Sun, Weifu, Saikov, Ivan, Shcherbakov, Vladimir, Alymov, Mikhail
• Format: Article
• Language: English
• Subjects: High entropy alloy; Mechanical property; Molecular dynamics; Uniaxial tension
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2021.102525

The microstructural evolution and deformation mechanism of AlxCoCrFeNi high-entropy alloys have been revealed from atomic level and the effects of Al concentration, temperature and strain rate on the mechanical properties of the high-entropy alloys have been studied. [Display omitted] •The microstructure evolution, deformation mechanism and the mechanical properties of the AlxCoCrFeNi high-entropy alloys have been explored.•The resulted twin boundaries, stacking faults, and shear bands lead to the sudden drop in stress after yielding point.•The increase of Al concentration and temperature has a negative impact in the tensile properties.•The dislocation densities decrease whereas the shear strain becomes distributed uniformly with increasing the temperature.•The increase of strain rate exerts positive role in the yield stress and yield strain. In this work, the microstructure evolution, deformation mechanism and the mechanical properties of the AlxCoCrFeNi high-entropy alloy (HEAs) under uniaxial tension have been explored using molecular dynamics simulations. The influencing factors including Al concentration, temperature and strain rate have been considered. Results show that the phase transforms from the original single face-centered cubic (FCC) structure into body-centered cubic (BCC), hexagonal close-packed (HCP) and amorphous structure and the atoms with BCC, HCP and amorphous structure increase whereas the atoms with FCC structure decreases with the increase of strain, especially after the yield strain. The increase of both Al concentration and temperature has a negative impact in the tensile properties of AlxCoCrFeNi HEAs including the Young’ modulus, yield stress and yield strain. The dislocation densities decrease whereas the shear strain becomes larger and distributed uniformly with the increase of the temperature. The high Al concentration can inhibit the reduction of Young’s modulus and yield stress with increasing the temperature. In contrast, the increase of strain rate leads to an appreciable hike in the yield stress and yield strain of HEAs but exhibits negligible influence on the Young’s modulus. The high Al concentration can amplify the effect of increasing strain rate on the Young’s modulus and yield stress. The dislocation density does not monotonically change with increasing the strain rate within the considered strain rate range of 108-2 × 1010/s, nonetheless in most cases the dislocation density decreases with increasing strain rate