Nanostructuring is a commonly employed method of obtaining superior mechanical properties in metals and alloys. Compared to conventional polycrystalline counterparts, nanostructuring can provide remarkable improvements in yield strength, toughness, fatigue life, corrosion resistance, and hardness, which is attributed to the nano grain size. In this review paper, the current state-of-the-art of synthesis methods of nanocrystalline (NC) materials such as rapid solidification, chemical precipitation, chemical vapor deposition, and mechanical alloying, including high-energy ball milling (HEBM) and cryomilling was elucidated. More specifically, the effect of various process parameters on mechanical properties and microstructural features were explained for a broad range of engineering materials. This study also explains the mechanism of grain strengthening using the Hall-Petch relation and illustrates the effects of post-processing on the grain size and subsequently their properties. This review also reports the applications, challenges, and future scope for the NC materials.

Nanocrystalline Materials: Synthesis, Characterization, Properties, and Applications

The influences of Ag content on the friction and wear properties of TiCN–Ag films

The influence of Ag content on the morphology, structure, hardness (H) and reduced Young's modulus (E), thermal stability, and oxidation resistance of TiAlSiN(Ag) coatings is investigated. The coatings were produced by DC reactive magnetron sputtering , with increasing Ag contents from 0 up to 15.9 at.%. All coatings exhibit a fcc type structure. The coating with 1.5 at.% Ag content displays the highest H and E values as a result of the coating densification and the grain refinement caused by the co-deposition of immiscible phases. Further Ag concentration degrades the H and E values of the coatings due to the incorporation of a softer Ag phase in the structure. Annealing at 800 °C in protective atmosphere for 2 h enhances the coatings crystallinity , with small increments in the H and E values. The dynamic thermal gravimetric oxidation curves reveal that Ag additions do not affect the starting point of oxidation of the coatings (~990 °C). However, it enhances their oxidation resistance. The improved oxidation resistance of the coatings with Ag incorporation is caused by the diffusion of Ag through the oxide scale to the surface, which modifies the composition of the Ti-Al-O layer, producing a more protective Al rich layer. 

TiAlSiN(Ag) coatings for high temperature applications: The influence of Ag alloying on the morphology, structure, thermal stability and oxidation resistance

Tribological performance under different environments of Ti—C—N composite films for marine wear-resistant parts

Thermal stabilization of nanocrystalline promoting conductive corrosion resistance of TiN–Ag films for metal bipolar plates

The invention discloses a self-hardening iron-based material for a shear blade. The self-hardening iron-based material is prepared from the following raw material components in percentage by mass: 3.0%-4.0% of C, 2.0%-3.5% of Si, 0.1%-0.6% of Mn, not more than 0.06% of P, not more than 0.02% of S, not more than 0.05% of Re, not more than 0.04% of Mg and the balance of Fe. The self-hardening iron-based material solves the problem that the prior carbon steel and alloy steel blade loses wear resistance and fatigue resistance due to movement or loss of the carbon layer and the hardening layer. Thepreparation method of the shear blade is simple in process, the manufacturing and processing cost of the material is greatly reduced, and the preparation method has good practical value.

Wang Ziyu

Papers

Thermal stabilization of nanocrystalline promoting conductive corrosion resistance of TiN–Ag films for metal bipolar plates

Self-hardening iron-based material for shear blade and preparation method of shear blade