Recent progress in the CoCrNi alloy system

Strange Metallicity and Magnetic Order in the CoNi(Cr/V) Medium-Entropy Alloy System

“…The major motivation for the theoretical studies is to understand the synergy between the strength and the ductility of the CoNiCr system and its relevance to the physical properties, such as the magnetism. The atomic radius misfit between the Co, Ni, and Cr was not large enough to generate significant lattice distortion; hence, from a traditional metallurgical point of view a relatively small solid solution strengthening was expected [ 29 ]. In sharp contrast, the CoNiCr system exhibited exceptional solid solution strengthening [ 13 , 24 ].…”

“…More recently, it has been observed that the outstanding properties of these MPEs are neither confined to equiatomic composition nor the increasing number of alloying elements (increasing entropy), which was validated after a systematic study on the subsets of the quinary FeNiCoCrMn single-phase alloy [ 5 , 23 ]. Among all the studied compositions, the CoNiCr (MEA) exhibited a significantly higher yield and the highest tensile strength and oxidation and corrosion resistance as compared to other binary, ternary, or quaternary MPEs, including the FeNiCoCrMn system for a large spectrum of temperatures [ 13 , 18 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. Both from the experimental and theoretical point of view, the CoNiCr MEA is an extremely interesting model system, where the atomic radii mismatch is not so large as to produce an observed solid solution strengthening [ 29 ].…”

“…Among all the studied compositions, the CoNiCr (MEA) exhibited a significantly higher yield and the highest tensile strength and oxidation and corrosion resistance as compared to other binary, ternary, or quaternary MPEs, including the FeNiCoCrMn system for a large spectrum of temperatures [ 13 , 18 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. Both from the experimental and theoretical point of view, the CoNiCr MEA is an extremely interesting model system, where the atomic radii mismatch is not so large as to produce an observed solid solution strengthening [ 29 ]. Extensive theoretical studies have been carried out to understand the underlying mechanism of the mechanical properties through the calculation of the stacking fault energies (SFEs) of the CoNiCr system [ 33 , 36 , 37 ].…”

“…Extensive theoretical studies have been carried out to understand the underlying mechanism of the mechanical properties through the calculation of the stacking fault energies (SFEs) of the CoNiCr system [ 33 , 36 , 37 ]. In this regard, the SFE is a crucial element in understanding the deformation mechanisms of metallic alloys [ 29 , 38 ]. Yet, the atomistic simulations, which consider the CoNiCr system as a random solid solution, have failed to predict the experimental SFE values correctly [ 28 , 36 , 37 ].…”

“…From a different perspective, it has been suggested that the atomic volume misfit has more impact on the phase stabilization and the SFE in the CoNiCr system than the atomic radius mismatch [ 29 , 32 ]. The Cr atom has around 10% more atomic volume than Ni and Co; potentially, many of the observed mechanical properties could be related to this large misfit.…”