Strengthening characteristics of CoCrNi alloys with different stacking fault energies

Quantifying the contributions of various strengthening mechanisms is essential for manipulating these mechanisms and designing novel alloys. Although CoCrNi alloys demonstrate exceptional mechanical properties, their strengthening characteristics remain to be investigated. In this work, we conducted in situ neutron diffraction tensile tests and characterized deformation microstructures for CoCrNi alloys with different stacking fault energies (SFEs). The dislocation strengthening characteristics and the role of planar faults were systematically investigated. A reduction in SFE restricts cross slip, thereby increasing the dislocation multiplication rate while decreasing the dislocation strengthening coefficient α. Additionally, a lower SFE facilitates the simultaneous activation of dislocations and planar faults, with dislocation strengthening consistently playing a dominant role. This work quantifies reasonable α values for CoCrNi alloys and identifies cross slip as a critical factor potentially influencing α value in face-centered cubic (FCC) alloys.