Formation of Defect Structure at the Atomic Level under Mechanical Loading of CoCrFeMnNi High-Entropy Alloys

摘要

The mechanisms of plasticity nucleation under compression and tension of single crystals of high-entropy alloys Co_(10)Cr_(10)Fe_(30)Mn_(30)Ni_(20) and Co_(30)Cr_(30)Fe_(10)Mn_(10)Ni_(20) are studied in the framework of the molecular dynamics method. The equilibrium distribution of chemical elements in alloys was obtained as a result of the relaxation of samples by Monte Carlo and molecular dynamics methods. Simulations were performed for bulk samples (with periodic boundary conditions in all directions) and thin films. The features of the nucleation and development of plasticity are significantly different for the considered stoichiometric compositions of the alloys. For single crystals of both compositions, the stacking faults and the bands with the hcp lattice structure are formed in the {111} planes. However, they nucleate and grow more intensively and at lower stresses in Co_(10)Cr_(10)Fe_(30)Mn_(30)Ni_(20) than in Co_(30)Cr_(30)Fe_(10)Mn_(10)Ni_(20). At further tension, twins are formed in the samples, but they are not observed during compression. Twinning is more pronounced in thin films.