Manganese is one of the abundant and cheap metal elements in the earth’s crust. As an additive in steel, it can enhance the impact and wear resistance of the alloy. It can also be used to replace Nickle in stainless steel to reduce the cost of the alloy. Xing et al. added different contents of Mn to the CoCrFeNi high-entropy alloy, and found that the addition of Mn had no effect on the microstructure of the alloy, and the alloy still maintained a single-phase FCC solid solution state, but the yield strength of the alloy increased first with the increase of the Mn content. After that, the yield strength of the alloy reaches a maximum of 319.6MPa when the alloy composition is CoCrFeNiMn. Manganese can not only enhance the wear resistance and corrosion resistance of the alloy, but also improve the mechanical properties of the alloy, but excessive Manganese will lead to the formation of chromium-rich phase, which will significantly reduce the compressive strength and ductility of the alloy. As an important constituent element of high-entropy alloys, Mn has a small radius difference from the commonly used principal elements such as Fe, Cr, and Ni in high-entropy alloys, and has a large solubility in alloys. The addition of Mn to high-entropy alloys mainly exists in the form of solid solution, which will not change the crystal structure of the alloy, but will cause the alloy to undergo solid-solution strengthening.
Chromium: As one of the metal elements with strong corrosion resistance, Cr is often added to traditional alloys to improve its corrosion resistance, and adding it to high-entropy alloys will significantly improve the mechanical properties of the alloys. Chen et al. found through the research on the hardness of AlTiFeNiCuCr x series high-entropy alloys that the increase of Cr content led to the increase of alloy hardness. Cr not only improves the corrosion resistance of high-entropy alloys, but also improves the mechanical properties of the alloys to a certain extent. Adding Cr to the high-entropy alloy will make the BCC or B2 phase structure appear inside the alloy, which will greatly improve the strength and hardness of the alloy, but the BCC and B2 phase will make the alloy hard and brittle, and the plasticity of the alloy will be reduced.