As one of the lightest metallic structural materials, magnesium (Mg) alloys possess numerous distinctive properties and are utilized across a broad spectrum of applications. However, the poor corrosion resistance of Mg alloys limits their application. Micro-arc oxidation (MAO) is an effective surface treatment method that enhances the corrosion resistance of Mg alloys. Nevertheless, the intrinsic porous structure of MAO coatings hinders significant improvement in corrosion resistance. Research indicates that the pre- and post-treatment processes associated with MAO markedly enhance the densification of the oxide coatings, thereby improving their overall performance. This paper aims to provide a comprehensive review and analysis of the effects of various pre- and post-treatment processes, highlighting key advancements and research gaps in improving MAO coatings on Mg alloys. An in-depth analysis of the crucial role of pre-treatment in optimizing interfacial bonding and post-treatment in enhancing coating density is conducted using electrochemical testing and scanning electron microscopy (SEM). Finally, the future development of pre- and post-treatment processes are discussed.

Wear-resistant coatings applied to the surface of copper and copper alloys through diverse advanced technologies can substantially enhance their wear resistance and broaden their application spectrum. This paper provides a comprehensive review of the development and current research status of wear-resistant coatings fabricated on copper and its alloys. It presents the research findings on the preparation of wear-resistant coatings using both one-step methods (such as laser cladding, electroplating, thermal spraying, cold spraying, electro-spark deposition, etc.) and two-step methods (chemical plating and heat treatment, electrodeposition and laser cladding, laser cladding and in situ synthesis, etc.). This paper provides an in-depth examination of the characteristics, operating principles, and effects of various coating techniques on enhancing the wear resistance of copper and copper alloys. The advantages and disadvantages of different coating preparation methods are compared and analyzed; meanwhile, a prospective outlook on the future development trends is also offered.

Liquid phase segregation of immiscible alloys has been investigated for decades. In this work, rare-earth Ce was studied as an additive for Al-Bi immiscible alloys. The addition of Ce restrained liquid phase segregation to obtain a uniformly dispersive microstructure. The experimental results indicated that in situ-precipitated intermetallic CeBi₂ compound acted as an inoculant for the heterogeneous nucleation of the Bi-rich droplets. The Bi-rich droplets nucleated on the CeBi₂ compound surface—a homogenous dispersed microstructure obtained via a heterogeneous nucleation route. We concluded that gravity segregation can be suppressed by the addition of rare-earth Ce.

The low hardness and insufficient wear resistance of aluminum and its alloys restrict their broader application in various fields. The application of surface protective coatings can effectively enhance the hardness and wear resistance of aluminum and its alloys. This article provides a comprehensive review of the recent research progress of wear-resistant coatings fabricated on aluminum and its alloys. The relevant achievements in the recent research works of preparing wear-resistant coatings by one-step methods (such as anodic oxidation, micro-arc oxidation, cold spraying, plasma spraying, and electrodeposition) and two-step methods (anodic oxidation and physical vapor deposition, micro-arc oxidation and sealing, magnetron sputtering, and plasma nitriding) are mainly introduced. The working principles of each coating preparation method, along with their impacts on the microstructure and tribological performance of the coatings, were systematically examined. Additionally, a comparative analysis was conducted to evaluate the advantages and disadvantages of each coating preparation method.

An NbC–Fe composite powder was synthesized from an Nb₂O₅/Fe/C mixture by electrochemical reduction and subsequent carbonization in molten CaCl₂–NaCl. The composite has a core–shell structure, in which NbC acts as the cores distributing in the Fe matrix. A strong bonding between NbC and Fe is benefit from the core–shell structure. The sintering and electrochemical reduction processes were investigated to probe the mechanism for the reactions. The results show that NbC particles about several nanometers were embraced by the Fe shell to form a composite about 100 nm in size. This featured structure can feasibly improve the wettability and sinterability of NbC as well as the uniform distribution of the carbide in the cast steel. By adding the composite into steel in the casting process, the grain size of the casted steel was markedly deceased from 1 mm to 500 μm on average, favoring the hardening of the casted steel.

Al-Bi immiscible alloys, as wear resistance material, have attracted increasing attention in the past. The solidification processing of alloys plays a significant role in the final solidification microstructure and properties of immiscible alloys. Here, we present a strategy to produce a homogeneous microstructure in Al-Bi alloys based on intermetallic compounds. With the addition of Sm and Ti, the effect on the microstructure and properties was discussed in detail. The Al-Bi-Sm-Ti alloys achieve high self-lubricating performance, referring to the values of the coefficient of friction and wear rate. The intermetallic compounds formed were regarded as the main anti-friction and anti-wear factors. The results of numerical simulation indicate that microsegregation in Al-Bi alloys was retarded based on the intermetallic compounds. The coefficient of friction of the Al-Bi-1Sm-2Ti alloy was 46.2% lower than that of the Al-Bi alloys at 300 m. This research provides a new perspective and guidance for designing and fabricating composites with superior self-lubricating properties.