Effects of Al2O3 micro/nanoparticles on the microstructure and corrosion behavior of W–Ni–Fe matrix through spark plasma sintering process

The purpose of this research is to examine the effect of Al2O3 micro/nanoparticles on the properties of the W–Ni–Fe matrix. The study involved analyzing the microstructure, hardness, density, and corrosion behavior of the W-4.9Ni-2.1Fe matrix with varying percentages of Al2O3 micro/nanoparticles (0.5, 1, and 1.5 wt%) that were sintered using the spark plasma method. The corrosion properties of different composites were studied using electrochemical impedance spectroscopy, Tafel polarization, and weight loss measurements. Furthermore, microstructural evaluations were carried out on samples before and after corrosion tests using optical and field emission scanning electron microscopy. The results indicated that a 1% increase in the percentage of Al2O3 nanoparticles led to approximately a 16% increase in the matrix hardness. This increase was attributed to the reduction in grain size and the distribution of pores in the nanocomposites. Tafel polarization measurements also showed that adding 1% Al2O3 nanoparticles resulted in an 83% improvement in the corrosion resistance of the W–Ni–Fe matrix in a 3.5 wt% NaCl solution. The improved corrosion resistance of the fabricated nanocomposites was attributed to the uniform distribution of Al2O3 nanoparticles in the matrix and reduction in the cathodic region. However, it was found that the formation of galvanic microcells was a critical cause of corrosion in micro-composites, leading to a reduction in corrosion resistance compared to the W–Ni–Fe matrix. Raman spectroscopy patterns indicated that Fe3O4, Fe(OH)2, NiO, and Ni(OH)2 were the main corrosion products.