Electrochemical characterization of Al84Ni9Y7 metallic glass after annealing process

Abstract In this work, the selected samples of Al84Ni9Y7 alloy in the melt-spun state and after annealing were tested in 3.5% NaCl solution with the aim to determine their potential application as structural materials. The electrochemical measurements indicated that corrosion current density changes with the increase of annealing temperature. The sample in the melt-spun state presents the lowest corrosion current density (icorr = 0.3 μA/cm2) and the highest polarization resistance (15.2 kΩcm2) among others. The results were also confirmed by electrochemical impedance spectroscopy (EIS) measurements. The representative EIS spectra of ribbons after 1 h of immersion indicated that the diameter of the loops observed from Nyquist plots for sample annealed at 573 K is higher comparing to others. It confirmed the increase of corrosion resistance of selected samples after heat treatment. The mechanical properties were also changed in a function of annealing temperature. The tensile strength and hardness obtained for the samples are changed with the increase of the annealing temperature. The highest hardness (524 HV) was obtained for ribbon annealed at 623 K. However, the highest tensile strength (196 MPa) was obtained for the as-spun sample. The XPS measurements were used to determine the elemental composition of sample surface after corrosion. The corrosion surfaces were identified to Al2O3, NiO, Y2O3 and Al(OH)3 compounds. The EDS and XPS results suggest that aluminum oxides and hydroxides were mainly formed as corrosion products on the surface of studied alloy.