Friction stir processing (FSP) has attracted much attention in the last decade and contributed significantly to the creation of functionally graded materials with both gradient structure and gradient mechanical properties. Subsurface gradient structures are formed in FSPed metallic materials due to ultrafine grained structure formation, surface modification and hardening with various reinforcing particles, fabrication of hybrid and in situ surfaces. This paper is a review of the latest achievements in FSP of non-ferrous metal alloys (aluminum, copper, titanium, and magnesium alloys). It describes the general formation mechanisms of subsurface gradient structures in metal alloys processed by FSP under various conditions. A summary of experimental data is given for the microstructure, mechanical, and tribological properties of non-ferrous metal alloys.

Additive manufacturing of metal materials is one of the most promising technologies in modern industry. A wide variety of current additive manufacturing techniques allow rapid prototyping and industrial production of different-sized products from various structural and functional materials. The structure and physical-mechanical properties of the metal products fabricated by electron-beam additive manufacturing (EBAM) within nonstationary metallurgy in a local molten pool often differ from those of the products fabricated by conventional metallurgy due to different crystallization mechanisms, sequence and completeness of phase transformations, and heterogeneous/homogeneous chemical composition of the resulting material. The possibility to control local metallurgical processes in the molten pool is the key advantage of the EBAM technology. It allows one to control the structure, composition, and properties of mono- and polymetallic, graded, composite and heat-resistant materials in order to obtain products with the desired chemical composition, macroscopic architecture, and microscopic structural parameters. As any new industrial technology, the EBAM method requires the development of scientifically based approaches to the choice of materials and production conditions. Here we provide an overview of the scientific approaches developed for electron-beam additive manufacturing of products from metals and alloys using wire or rods as a feedstock. The range of the studied materials includes additive materials based on copper, bronze, aluminum, nickel, titanium alloys, and different steels, as well as aluminum-based functionally graded materials and copper-based graded materials. The most important research findings are summarized.