The effect of ultrasonic field on the microstructure and corrosion behavior of Fe-based amorphous coating applied to selective laser melting

Abstract

This study was conducted to investigate the effect of the ultrasonic field on the preparation of amorphous/crystalline Fe-based coatings. For this purpose, Fe86.3Si 5.9B3.2Cr4.6 (wt.%) powder was deposited on GTD-111 superalloy substrate with and without ultrasonic field by selective laser melting method. After coating, the corrosion behavior, microstructure, and hardness of the amorphous coating were investigated. The results showed that in conditions without ultrasonic vibration, the growth of grains starts in columnar form. At the same time, the use of an ultrasonic field inhibits columnar growth and creates equiaxed grains. In addition, the ultrasonic field increased the amorphous phase by 34.5%. This is attributed to the increased solidification rate caused by the cavitation effect. The experimental results of corrosion show that the self-corrosion current density of 6.83×10-7 A⋅cm2 is obtained due to the refinement of the microstructure and the increase of the amorphous phase. The wear results showed that the increase in the amorphous phase, as well as the decrease in the grain size, reduction in the grain ratio, and the increase in the tendency to equiaxed grains when using the ultrasonic field, reduce the coefficient of friction by 97%.