| Abstract Scope |
Crystalline defects are of fundamental importance in understanding and thereby tailoring the macroscopic mechanical responses of complex concentrated alloys (CCAs). Particularly in microstructural metastability engineering, appreciable interest has aggregated in transformation-induced plasticity or twinning effect. However, the inherent operative unit, stacking faults, have not yet drawn abundant attention. By investigating a CoCrNiW CCA, we will reveal a lesser-explored deformation “faulting” response. Through coupled in-situ synchrotron and ECCI experiments, we will show that the nucleation of extensive stacking faults is acting as the major plasticity carrier within this CCA, providing macroscopic strain hardenability. We will demonstrate that this sort of faulting mechanism is largely ascribed to a negative stacking fault energy, for which our in-situ ECCI experiment will provide a direct validation. Broader insights into the role of multi-layer generalized stacking fault energy landscape will also be discussed to complement the current thermodynamic-guided design strategy of metastable CCAs or high-entropy alloys. |