Slurry Erosion–Corrosion Resistance of MoNbTaTiZr High Entropy Alloy

Slurry erosion–corrosion is a severe issue for many engineering components used in marine, petrochemical, and agricultural sectors. The deleterious effects of the slurry erosion–corrosion significantly lower the service life and enhance the maintenance cost. For limiting the slurry erosion–corrosion effects, there is a need for high-performance advanced materials. In the present work, equimolar MoNbTaTiZr high-entropy alloy (HEA) was developed, and its slurry erosion–corrosion behavior was investigated. For comparison, conventionally used stainless steel SS316L was also investigated. The detailed microstructural characterization showed the presence of a two-phase bcc crystal structure in the HEA. The major bcc phase was predominantly composed of Ta, Mo, and Nb with the interdendritic region being rich in Ti and Zr. The MoNbTaTiZr HEA showed 2 times higher hardness than the SS316L steel. Under slurry erosion–corrosion condition, the HEA showed 3.5 times higher resistance while under erosive conditions, two times better performance than the reference material. The analysis of the eroded surface morphology showed the presence of a mixed ductile–brittle erosion response for the HEA. The improved performance of the HEA is predominantly related to the high hardness and extremely high corrosion resistance. Electrochemical corrosion testing revealed that the HEA has 80 times lower current density than SS316L and high pitting resistance, resulting in low corrosion rates. The electrochemical impedance spectroscopy (EIS) findings showed a denser and highly stable passive layer. The results indicated that MoNbTaTiZr HEA could be effectively used for countering the slurry erosion–corrosion and corrosive conditions.