Temperature-dependent short-range order formation and its effects on yield strength in single crystals of the equiatomic Cr-Mn-Fe-Co-Ni high-entropy alloy

Short-range order (SRO) has attracted great research interest in the field of high- and medium-entropy alloys (HEA/MEAs). In order to understand the effects of SRO on mechanical properties, it is indispensable to experimentally quantify the existence of SRO. In this work, the evolution of SRO in the equiatomic Cr-Mn-Fe-Co-Ni, the prototype HEA, has been investigated as a function of temperature by electrical resistivity measurements and the effects of SRO on the yield strength has also been investigated by compression tests at room temperature. SRO is found to occur in a homogeneous manner in the temperature range of 673-973 K with 673 K being the peak temperature. This is very similar to the equiatomic Cr-Co-Ni medium- MEA, although the kinetics for SRO is much faster in the equiatomic Cr-Mn-Fe-Co-Ni HEA due to the faster atomic diffusion. SRO does not have any significant impact on the yield stress at room temperature regardless of the degree of SRO. Being consistent with this, no significant change in dislocation structure and stacking fault energy is observed regardless of how significantly SRO develops. • The evolution of SRO was monitored by electrical resistivity in the equiatomic Cr-Mn-Fe-Co-Ni HEA. • SRO occurs homogeneously during annealing in the temperature range from 673 to 873 K. • The CRSS, dislocation structures and SFE do not change with the formation of SRO.