Manufacturing an ultra-low-sulfur CoCrFeMnNi high-entropy alloy by slagging through induction melting with ferroalloys feedstock

• Published in: Journal of alloys and compounds 2022-12, Vol.928, p.167080, Article 167080
• Main Authors: Duan, Shengchao, Kang, Jiyeon, Cho, Jinhyung, Lee, Minjoo, Mu, Wangzhong, Park, Joo Hyun
• Format: Article
• Language: English
• Subjects: Alloys; Aluminous refractories; Aluminum oxide; Calcium aluminate; Calcium oxide; CaO-MgO-Al 2 O 3 slagging; CaO-MgO-Al2O3 slagging; CoCrFeNiMn high -entropy alloy; Desulfurization; Desulfurizing; Ferroalloys; High entropy alloys; Induction melting; Magnesium oxide; Manufacturing; Mass transfer; Mechanical properties; Melting furnaces; MnS inclusion; Mushy zones; Nickel; Nickel base alloys; Raw materials; Slag; Slagging; Solidification; Sulfur; Sulfur content
• ISSN: 0925-8388; 1873-4669; 1873-4669
• DOI: 10.1016/j.jallcom.2022.167080

Commercial ferroalloys are used in the manufacturing of a CoCrFeMnNi high-entropy alloy (HEA) due to their price advantage and the productivity of the manufacturing process. However, elemental impurities such as sulfur in ferroalloys can undermine the mechanical properties of HEAs. Therefore, the desulfurization behavior of a CoCrFeMnNi HEA using the CaO-MgO-Al2O3 (CAM) slagging method with alumina or magnesia refractories and ferroalloys raw material feedstock was investigated in an induction melting furnace at 1773 K to determine how to control the cleanness of the HEA. The resulting desulfurization ratios of the alloy were approx. 47% when refined by the CaAl2O4-MgAl2O4(CA-MA)-saturated slag in an Al2O3 refractory, whereas 94% when refined by the CaO-MgO(C-M)-saturated slag in a MgO refractory. The overall mass transfer coefficients of sulfur for the HEA refined by the CA-MA- and C-M-saturated slags at 1773 K were ko=1.4×10−6m/s and ko=2.0×10−6m/s, respectively, which are lower than the coefficients of iron- and nickel-based alloys at the same experimental conditions. The MnS inclusion particles can precipitate in the mushy zone rather than the liquid region when the solid fraction is close to 1.0, i.e., at the final stage of the solidification. The theoretical radius of MnS increases from 0 to 1.6 µm when the sulfur content rises from 3 ppm to 60 ppm, according to the hypothesis that the mass transfer of sulfur in the HEA is the rate-controlling step. •Novel procedure for manufacturing high-entropy alloys using commercial ferroalloys feedstock was proposed.•Impurity sulfur was effectively removed to 3 ppm by slagging method in an induction melting furnace without vacuum.•MnS inclusion, which is detrimental to alloy properties, was not precipitated in a produced high-entropy alloy.