An Al-Zn-Mg-Cu alloy has high specific strength, good corrosion resistance, fracture toughness and fatigue resistance. It is one of the most important structural materials in the fields of aviation, aerospace, weapons and transportation; in particular, it plays a huge role in the field of aerospace. In order to optimize the strength, toughness and corrosion properties of an Al-Zn-Mg-Cu alloy, the focus of research on this alloy has always been on the alloying process. The effects of the main alloying elements, trace alloying elements and rare earth elements on the microstructure and properties of Al-Zn-Mg-Cu alloys are briefly introduced in this paper, and future research directions are proposed.

At present, in the aviation industry, titanium alloy is mainly used to manufacture parts such as compressor discs, blades, and the casings of aircraft engines. When titanium alloys are in service, high temperature is generated due to high-speed running friction, which requires them to have high-temperature oxidation resistance and friction resistance. If they are used in an environment with salt corrosion, titanium alloys will face thermal corrosion, which limits their wider practical applications. At present, there are many methods to protect titanium alloys. This paper mainly includes alumina-based coatings and some preparation methods. The characteristics and functional mechanisms of three functional coatings for the service environment, namely highly temperature-resistant alumina-based coating, thermal corrosion-resistant alumina-based coating, and wear-resistant alumina-based coating, are summarized. Finally, the development direction of composite coatings of titanium and titanium alloys for a complex service environment is suggested.