Amorphous alloy reinforced Cu-based immiscible coatings by laser melting deposition: Separation mechanism and corrosion behavior
Shengfeng Zhou, Junjie Yang, Cheng Deng, Jianbo Jin, Lianxi Hu, Yang Lü
Abstract
In order to clarify the effect of Fe-based amorphous alloy on the separation mechanism and corrosion behavior of Cu-based immiscible coatings, 10 wt% Fe-based amorphous powder was designed into 90 wt% pure Cu powder to produce the amorphous alloy reinforced Cu-based immiscible coatings by laser melting deposition. The self-organized microstructure and corrosion behavior of immiscible coatings with different laser energy densities were investigated. When the different laser energy densities are adopted, many carbides (M<sub>23</sub>C<sub>6</sub> and M<sub>12</sub>C) are dispersed in the lower α-Fe layer and large amounts of α-Fe particles containing carbides are embedded in the upper ε-Cu layer due to liquid phase separation. With increasing laser energy density (LED), the α-Fe dendrites are coarser and the area of carbides decrease. The interface of coating and substrate experiences a transition from “poor bonding (gaps) to “good bonding” and “crack debonding”. Moreover, the corrosion characteristics of immiscible coatings also experience a transformation from “crevice corrosion” to “enhanced protection of passive films” and “reduced protection of passive films”. As a result, the corrosion resistance increases first then decreases and the immiscible coating deposited by the LED of 31.25 J/mm<sup>2</sup> exhibits the highest corrosion resistance. © 2023 The Authors.