The corrosion behaviour of CoCrFeNi-x (x = Cu, Al, Sn) high entropy alloy systems in chloride solution

Improved Tribocorrosion Resistance by Addition of Sn to CrFeCoNi High Entropy Alloy

“…It reveals that CrFeCoNi contains (within an experimental error of ±1 at.%) the solid solution phase of Co0.25Cr0.25Fe0.25Ni0.25, which is known to adopt the FCC structure [17]. Conversely, CrFeCoNiSn forms a dual phase structure, shown previously by XRD to be CrFeCoNi FCC phase and Ni1.5-1.63Sn hexagonal phase [17]. The BSE micrographs of HEA samples gathered here ( Figure 2) correspond with these earlier results.…”

“…Table 1 shows the composition of distinguishable phases in CrFeCoNi and CrFeCo-NiSn, determined by EDS. It reveals that CrFeCoNi contains (within an experimental error of ±1 at.%) the solid solution phase of Co0.25Cr0.25Fe0.25Ni0.25, which is known to adopt the FCC structure [17]. Conversely, CrFeCoNiSn forms a dual phase structure, shown previously by XRD to be CrFeCoNi FCC phase and Ni1.5-1.63Sn hexagonal phase [17].…”

“…As described in previous research by Muangtong et al [17], the different phases make up the CrFeCoNiSn alloy stems from Sn, with positive mixing enthalpy values with Cr As described in previous research by Muangtong et al [17], the different phases make up the CrFeCoNiSn alloy stems from Sn, with positive mixing enthalpy values with Cr and Fe and a negative one with Ni, leading to a change from the single phase of CrFeCoNi to the dual phase of CrFeCoNiSn. From the data in Table 2, the negative ∆H mix,<ij> of the Ni-Sn couple leads to the formation of the Ni-Sn intermetallic compound [17,[27][28][29]. On the other hand, other potential couples (Co, Cr, and Fe with Sn) have positive ∆H mix,<ij> values and do not interact with the Sn-rich phase.…”

“…On the other hand, other potential couples (Co, Cr, and Fe with Sn) have positive ∆H mix,<ij> values and do not interact with the Sn-rich phase. As well as this, the slightly negative ∆H mix,<ij> value of each other atomic couple (those involving Co, Cr, Fe, and Ni), except for the zero ∆H mix,<ij> value of the Co-Ni pair, contributes to generating the CrFeCoNi FCC phase [17,28,29].…”

“…Therefore, this work explores the tribocorrosion resistance, corrosion properties, and hardness of a four component equiatomic HEA, CrFeCoNi, and also the same alloy with an addition of Sn to make the five component equiatomic HEA CrFeCoNiSn. Previous investigations on these alloys have shown that the former produces a single phase FCC solid solution structure, and the second produces a two phase structure consisting of an FCC solid solution and an intermetallic phase [17]. Both were also found to have good resistance to corrosion in a static NaCl solution, and to possess good hardness.…”