Manufacturing a high-clean CoCrFeMnNi system alloy by slag treatment with ferroalloys feedstock

Abstract

Commercial ferroalloys are used in the manufacturing of a CoCrFeMnNi system alloy 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 system alloy 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 alloy. 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 oxide inclusions MnAl2O4 and MgAl2O4 can steadily exist in the alloy melted in Al2O3 and MgO crucibles with CaO-MgO-Al2O3 slag saturated CA-MA and C-M content, respectively, 1773 K. The alloy melted in the MgO crucible had a higher cleanness compared with that melted in the Al2O3 crucible, indicating that the MgO crucible with CaO-MgO-Al2O3 slag saturated CM content is suitable for refining the CoCrFeMnNi system alloy