A new study on the electrochemical behavior and thermal stability of W-4.9Ni-2.1Fe-xAl2O3 composites

The present study investigates the influence of adding micro/nanoparticles of Al2O3 (0.5-1.5 wt%) on the microstructure, electrochemical behavior, and thermal stability of a W-Ni-Fe matrix sintered by the spark plasma process. Corrosion characteristics were assessed through Tafel polarization and electrochemical impedance spectroscopy techniques in a 0.1 M HCl solution. The extent of corrosion was evaluated by examining the specimen surfaces before and after the corrosion test using field emission scanning electron microscopy and x-ray diffraction methods. Additionally, thermo-gravimetric analysis was employed to investigate the weight loss behavior and thermal stability of the composites up to 1000 degrees C in dry air atmosphere. The nanoparticles of Al2O3 significantly enhanced the corrosion resistance of the W-4.9Ni-2.1Fe matrix, with up to 90 % improvement observed in the presence of 1 wt% nanoparticles in the HCl solution. The uniform dispersion of nanoparticles throughout the matrix caused a decrease in the grain size and the cathodic area. Furthermore, the nanocomposites exhibited superior thermal behavior and minimal weight changes, as indicated by the thermoanalytical results. The thermal stability of the composites was assessed, and it was found that the specimen incorporating 1 wt% nanoparticles exhibited the greatest thermal stability, characterized by a 6 % enhancement in thermal resistance.