Alloys Nanopowders

Alloys Nanopowders List

Nanoparticles have significant volume effects, surface effects, quantum size effects, etc., so they exhibit some special phenomena, such as a drop in melting point, lattice distortion, melting overheating, phase change, and spontaneous diffusion at room temperature. For alloy nano-powders, this size effect will inevitably have a significant impact on the alloy behavior and alloy phase structure of the nanoparticles, which will be significantly different from the characteristics of conventional alloys and large particle powders.

Figure 1. Elemental characterization of alloy nanopowders.

Applications:

• Catalyst: Alloy nanopowders is widely used as a catalyst due to its high surface activity and large specific surface area. For example, Fe-Co nanopowders is used for the catalytic reaction of CO and +H₂; Fe-Mo nanopowders is used as a catalyst for the synthesis of carbon nanotubes by CVD.
• Magnetic materials: Because of its high coercivity, alloy nanopowders have broad application prospects as magnetic materials. The magnetocrystalline anisotropy of Fe-Pt nano powder is greater than 107 erg/cm3, which can be used as a perpendicular magnetic recording material; Fe-Nd-B nanopowders is suitable for preparing magnetic refrigeration materials, permanent magnet materials and magnetic detectors; Fe-Co nanopowders can be made into magnetic credit cards, magnetic keys, magnetic tickets, etc.
• Lubricant: Adding alloy nanopowders to lubricating oil in a proper way can obtain a new type of lubricating oil with excellent performance. Copper alloy nanopowders can be modified on the surface of the powder, which can overcome the self-polymerization phenomenon of copper alloy nanopowders in lubricating oil, can be uniformly and stably dispersed in lubricating oil, and can prevent the secondary accumulation and precipitation of nanopowders peaks.
• Absorbing materials: Interfacial polarization and multiple scattering caused by dangling bonds on the surface of particles are important absorbing mechanisms for alloy nanopowders. Ferroalloy nanopowders not only has good absorbing performance, but also has the advantages of wide frequency band, light weight, thin thickness, etc. It is a very promising absorbing material. Fe-Ni nanopowders has excellent microwave absorption characteristics not only in the centimeter wave band but also in the millimeter wave band.
• The metallurgical field: Due to the high specific surface area and high chemical activity of alloy nanopowders, the sintering temperature of the powder is low. Therefore, it can be used as a sintering aid in the powder metallurgy process to shorten the heating cycle of the sintering process, and even reduce the sintering temperature. In addition, alloy nanopowders can be used to prepare powder metallurgical coatings, such as using lasers to connect the powder to glass, or to melt powder gel onto the substrate.

Preparation method:

There are many methods for preparing alloy nano powders, such as vapor phase evaporation in low-pressure inert gas, CVD, particle sputtering and so on. Among the above methods, the arc, plasma and laser heating evaporation methods have the characteristics of fast heating speed and high temperature, and are ideal methods for preparing alloy nano powders containing high melting point metals.

References

1. Dustin M. Clifford, Carlos E. Castano, Melissa H. M. Tsui, Jessika V. Rojas and Everett E. Carpenter. Tailoring the magnetic properties of Fe_xCo_(1−x)nanopowders prepared by a polyol process. Dalton Trans., 2017, 46, 10364–10373.
2. Speranta Tanasescu, Alexandru Milea, Oana Gingu, Florentina Maxim, Cristian Hornoiu, Silviu Preda and Gabriela Sima. A correlation between thermodynamic properties, thermal expansion and electrical resistivity of Ag–28% Cu nanopowders processed by the mechanical alloying route. Phys. Chem. Chem. Phys., 2015, 17, 28322-28330.