Advanced Materials for Mechanical Engineering: Ultrafine‐Grained Alloys with Multilayer Coatings

Abstract

Research has demonstrated that the formation of a bulk ultrafine‐grained (UFG) structure in metals and alloys through severe plastic deformation (SPD) enables increasing of their strength properties and decreasing of the temperature range of superplasticity. Designers and process engineers generally show a great interest in such materials because the development of mechanical engineering industries places ever‐increasing demands on the performance properties of commercial alloys, especially for parts operating under extreme conditions. One of the approaches for a comprehensive enhancement of the performance characteristics of structural materials is a combination of a UFG structure in the bulk of a material, providing an increase in strength, and an additional surface modification providing resistance to erosion and corrosion damage. As a result, a set of material service properties can be enhanced, which is difficult to achieve through only metal nanostructuring or only surface modification. This approach has been demonstrated through an example of UFG titanium alloys produced by SPD, including those with nanostructured multilayer TiVN coatings of different “architectures.” Accordingly, herein, the trends, problems, and prospects of surface modification for the innovative application of structural UFG titanium alloys in advanced mechanical engineering are examined.

Superplastic‐Like Behavior and Enhanced Strength of a Two‐Phase Titanium Alloy with Ultrafine Grains

“…Recent studies of the long‐term strength of the UFG Ti–6Al–4V alloy at operating temperatures (not higher than 350 °C) show its obvious advantage over its coarse‐grained counterpart. [ 27 ] As for the VT8M‐1 alloy, in a recent work, it was observed that the UFG samples at the operating temperature (400 °C) withstand 100 h without destruction at a significant ultrahigh voltage, after the CG samples. [ 28 ] This behavior was explained by the presence of silicides, which fix the grain boundaries and prevent the motion of dislocations during creep tests.…”

Superior properties and behaviour of coatings produced on nanostructured titanium by PEO coupled with the EPD process

“…It played a vital role during the coating process and formed dense and compact coating. Due to that, the coatings produced on n-Ti exhibited a higher critical load compared to CG-Ti coatings [16].…”

“…Among these techniques, electrochemical modification processes like anodisation and plasma electrolytic oxidation (PEO) are cost-effective, ecofriendly, and the simplest processes [15]. Semenova et al documented those coatings produced on ultrafinegrained titanium (UFG Ti) exhibited considerable improvement in the adhesive strength and hardness due to a greater number of propagation and growth points in the coating development process and compact coatings produced than the CG-Ti [16]. Thick and highly adherent oxide coatings can be produced on Mg, Ti, Zr, Al, Nb, and their alloys by the PEO process [17][18][19][20][21].…”

Efficient Prediction of Grain Boundary Energies from Atomistic Simulations via Sequential Design

“…Grain boundaries (GBs) play an important role in materials science but they are still among the least understood crystal defects. Nano-structured materials, that is materials with a high density of GBs, dominate the development of new technologies for energy harvesting and storage, [2] for data processing, but also of solutions for structural applications, [16,29] where the presence of DOI: 10.1002/adts.202100615 interfaces leads to strengthening of the material. [4,9] The stability of such nanostructures can be tuned by the chemical composition, or rather the distribution of chemical elements in the microstructure and their segregation to grain boundaries.…”