The corrosion behavior of refractory bcc high-entropy alloys in molten cerium

Two novel refractory high-entropy alloys (RHEAs), TaNbTiW0.1Cr and TaNbTiW0.5V, were designed and fabricated to investigate their corrosion behavior after being held in molten cerium at 1200°C for 50 hours. The corrosion performance of these alloys was compared with that of MoNbTaW and MoNbTaWV. Among the four alloys, MoNbTaW demonstrated the best corrosion resistance, with the lowest average corrosion rate of 0.035 μm h-1, followed by TaNbTiW0.5V, which exhibited an average corrosion rate of 0.385 μm h-1. The MoNbTaW exhibits excellent resistance, with no significant surface changes. In contrast, MoNbTaWV shows deeper, smooth corrosion characterized by minor pitting but no substantial cracking. The TaNbTiW0.1Cr, initially homogeneous, undergoes preferential corrosion in the inter-dendritic regions, leading to crack formation. The TaNbTiW0.5V displays surface corrosion pits and cracks, with limited diffusion. Energy Dispersive Spectroscopy (EDS) analysis indicates that Cr is the most susceptible to corrosion, followed by Ti and Nb, while Ta and W exhibit greater resistance. These variations in corrosion behavior are attributed to the differing solubilities of these elements in molten cerium.