Mechanical Properties of Al_xCoCrFeNi High-Entropy Alloy: A Molecular Dynamics Study

The fabrication process of the high-entropy alloys (HEAs) at the atomic scale was investigated numerically through molecular dynamics (MD) approach, with which the micro-structures of Al_xCoCrFeNi were analyzed. The mechanical properties of the fabricated specimens with different Al contents subjected to axial loads were explored at different temperatures. Numerical results show that the high-entropy alloys Al_xCoCrFeNi undergoes the elastic, yielding and plastic stages in order when subjected to tensile. After yielding, dislocation lines emerge in the material, followed by the stacking faults and twins. The material produces inhomogeneous plastic deformation with the continuous generation and disappearance of dislocations. This analysis suggest that the lattice distortion effect is induced by the radius difference between Al atoms and other atoms, additionally, the binding force between them affects the Young's modulus and yield stress of high-entropy alloys. Moreover, the increase of temperature leads to more severe thermal vibration between metal atoms, larger atomic dynamic energy, increasing distance between atoms, while decreasing binding force between atoms, thereby resulting in a decrease of alloy elastic modality and yield stress. The effect of temperature is similar to that of the lattice distortion.