Interaction between screw dislocations and intrinsic/extrinsic stacking faults in CoNiCrFeMn high-entropy alloys: a molecular dynamics study

D Wu and SS Guo and MF Xiao and SY Shuang and GZ Kang and X Zhang, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, 33, 055006 (2025).

DOI: 10.1088/1361-651X/ade0df

Stacking faults and deformation twinning, promoted by low stacking fault energy, act as significant barriers to dislocation slip, enabling sustained strain hardening in CoNiCrFeMn high-entropy alloys (HEAs). Understanding the interactions between dislocations and stacking faults is crucial for elucidating the strengthening mechanisms in HEAs. In this study, molecular dynamics simulations are performed to investigate the interaction between screw dislocations and intrinsic/extrinsic stacking faults in CoNiCrFeMn HEAs. For comparison, simulations on pure Ni are included to highlight the effects of chemical fluctuations and lattice distortions unique to HEAs. The results show that in both HEAs and Ni, screw dislocations transmit through stacking faults as the primary interaction mode. However, the transmission mechanisms differ significantly. In pure Ni, screw dislocations fully constrict into perfect dislocations before crossing into the adjacent grain. In HEAs, the transmission process is stress-dependent. At high stress, the leading partial interacts directly with the stacking fault, whereas at low stress, extended dislocations undergo partial constriction to increase the driving force on the leading segment before transmission. These findings reveal distinct interaction behaviors and strengthening mechanisms in HEAs, offering insights into microstructural design strategies for enhancing alloy strength.

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