Researchers cut impurities in advanced metals using cheaper raw materials
Scientists have developed a cost-effective method to manufacture high-entropy alloys—materials used in aerospace and power generation—by repurposing commercial ferroalloys and removing harmful impurities through slag refining. The breakthrough could lower production costs while maintaining the purity standards required for high-performance applications.
Originaltitel: Manufacturing ultra-low sulfur and oxygen (FeCrCoMnNi)100-xCx high-entropy alloys using a commercial ferroalloy feedstock via induction melting and slag refining
<p>Commercial ferroalloys, such as high-carbon ferromanganese (HCFeMn), low-carbon ferrochromium (LCFeCr), and ferronickel (FeNi) alloys were chosen as the raw materials for the sustainable manufacturing of FeCrCoMnNi-based high-entropy alloy (HEA) with differing carbon contents due to their cost-effectiveness and the efficiency of the manufacturing process. The carbon content in the HEA prepared by this method originates from the ferroalloys themselves, called self-alloying . The effect of the carbon content on the phase composition, grain size and microhardness of three HEAs were investigated. Therefore, impurity control (desulfurization and deoxidation) during ferroalloy-based melting and refining was systematically investigated for the FeCrCoMnNi HEA with varying carbon contents (0.3, 0.7, and 1.8 at%) using the CaO–Al2O3–MgO (CAM) ternary slag in an induction melting furnace at 1773 K. The sulfur content in the alloys prepared by this method was less than 6 ppm and the oxygen content less than 13 ppm. The overall mass transfer coefficient of sulfur ko(s) in the three types of HEA was between 2.0 × 10−6 m/s and 3.0 × 10−6 m/s at 1773 K. The kinetic model of deoxidation of HEA refined by CAM slag was also established, and the mass transfer coefficient of oxygen (km(O)) ranging from 2.0 × 10−7 m/s to 4.0 × 10−7 m/s in the different compositions of FeCrCoMnNi- x C HEA at 1773 K, indicating that the oxygen in HEA is more difficult to be removed compared with other metallic systems such as steels, Ni-base alloys, etc.</p>