The role of compositional complexity in the increased fracture resistance of high entropy alloys: Multi-scale atomistic simulations

• Published in: Computational materials science Vol. 235; p. 112758
• Main Author: Farkas, Diana
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2024
• Subjects: Atomistic Simulation; Fracture Behavior; High Entropy Alloys; High Entropy Alloys; Atomistic Simulation; Fracture Behavior
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2023.112758

[Display omitted] This paper investigates the role of compositional complexity in the fracture behavior of a model quinary high entropy FCC alloy. The simulations are based on a multi-scale technique bridging continuum fracture mechanics with massively parallel molecular dynamics techniques at the atomistic level to study the deformation mechanisms. The atomistic part is based on empirical interatomic potentials and study the crack tip plasticity response for increasingly higher stress intensity factors. Crack blunting/propagation tests were performed and the material response analyzed using various techniques, focusing on the role that the local composition in the random alloy plays in the deformation mechanisms and the competition between dislocation emission from the crack tip and cleavage. Crack tip plasticity is studied in the complex alloy and in a corresponding “average atom” single component interatomic potential tailored to have the same average properties as the complex alloy but no local compositional complexity. Five different crystallographic orientations are studied and the complex high entropy alloy presents a higher fracture resistance than the average atom material for three of these orientations. The additional fracture resistance is shown to be due to enhanced dislocation emission from the crack tip and crack arrest in certain locations in the complex alloy system.