Al-Cu-Fe quasicrystalline foams represent a new class of materials with a unique combination of lightness, high porosity, and potentially excellent mechanical properties. These foams, consisting of a metal matrix based on aluminum, copper and iron with a quasi-crystalline structure, attract considerable attention of researchers due to the prospects of their application in various fields, including structural materials, damping elements, filters and catalysts.
The microstructure of quasicrystalline Al-Cu-Fe foams is characterized by a complex hierarchical organization. It consists of a cellular structure formed by thin walls, the basis of which is a metal matrix with quasicrystalline particles dispersed in it. The cell size, wall thickness, and volume fraction of the quasicrystalline phase are key parameters that determine the mechanical properties of foam.
The use of various production methods, such as powder metallurgy using sintering agents or melting methods with subsequent foaming, allows you to control the morphology and distribution of pores in the foam. In particular, the addition of sintering agents, such as TiH2, contributes to the formation of a more uniform microstructure with a smaller pore size and improved cell wall connectivity.
High-resolution microscopy, including scanning (SEM) and transmission (TEM) electron microscopy, is essential for detailed microstructure analysis. SEM allows you to visualize the overall morphology of the foam, while TEM reveals the details of the structure of quasicrystalline particles and their interaction with the metal matrix at the atomic level. Electron diffraction analysis (EDX and SAED) can identify the phase composition of the foam and determine the crystalline or quasi-crystalline structure of the phases present.
The mechanical properties of quasicrystalline Al-Cu-Fe foams are the subject of intensive research. These foams exhibit typical compression behavior of foam materials, characterized by an elastic region, a stress plateau under constant deformation, and subsequent compaction. However, unlike conventional metal foams, the presence of a quasicrystalline phase has a significant effect on the mechanical behavior.
The compressive strength and modulus of elasticity of quasicrystalline foams depend on many factors, including foam density, cell size, cell wall thickness, and volume fraction of the quasicrystalline phase. An increase in foam density usually leads to an increase in strength and modulus of elasticity, since this is due to a decrease in the size of cells and/or an increase in wall thickness. The presence of a quasicrystalline phase can contribute to foam hardening, especially at high volume fraction.
Mechanisms of deformation of quasicrystalline foams under compression include bending and destruction of cell walls, as well as plastic deformation of the metal matrix. Quasicrystalline particles can play a role in preventing the propagation of cracks and thereby increase the fracture toughness of the foam. However, if the concentration is too high, the quasicrystalline phase can lead to embrittlement of the material.
Studies of the effect of temperature on the mechanical properties of quasicrystalline foams show that compressive strength usually decreases with increasing temperature. This is due to a decrease in the strength of the metal matrix at elevated temperatures. However, quasicrystalline particles can maintain their stability at high temperatures, thereby providing some thermal stability to the foam.
Various factors related to both the production process and the material composition have a significant impact on the microstructure and mechanical properties of quasicrystalline Al-Cu-Fe foams.
Alloy composition: The optimal ratio of Al, Cu, and Fe is necessary for the formation of a quasicrystalline phase. Deviations from this ratio can lead to the formation of other metal phases that can affect the mechanical properties of the foam.
Production technology: The method of producing foam has a significant impact on the microstructure. For example, the use of sintering agents can lead to improved cell wall connectivity.
Process Parameters: Temperature, time and pressure during sintering or foaming play an important role in the formation of microstructure and, consequently, mechanical properties.
Due to their unique combination of properties, Al-Cu-Fe quasicrystalline foams have the potential to be used in a variety of applications.
Construction materials: High strength with low weight makes these foams attractive for use in structures that require high specific strength.
Damping elements: High porosity ensures efficient energy absorption, making these foams suitable for use in damping elements that reduce vibrations and shocks.
Filters: The controlled porosity makes these foams suitable for use as filters for liquids and gases.
Catalysts: The high surface area of quasicrystalline particles can be used in catalytic reactions.
Quasicrystalline Al-Cu-Fe foams represent a promising class of materials with a unique combination of microstructural and mechanical properties. Further research aimed at optimizing the composition, process parameters, and microstructure will allow us to fully realize the potential of these materials for various applications. Research into improving tensile strength, fatigue strength, and corrosion resistance is also needed to expand the scope of these materials. The development of new production methods that allow controlling the distribution of cell size and orientation of quasicrystalline particles is also an important area of research.
Author: S. Shuang, Z.Y. Ding, D. Chung, S.Q. Shi, Y. Yang
Institute: M.A. Suárez, M.F. Delgado-Pamanes, J.F. Chávez-Alcalá, A. Cruz-Ramírez, I. Guadarrama, I.A. Figueroa, Departamento de Materiales, DCBI, Universidad Autónoma Metropolitana, Unidad Azcapotzalco, Av. San Pablo 180, Col. Reynosa T., 02200 Ciudad de México, México, Instituto Politécnico Nacional – UPIIZ, Blvd. del Bote s/n, Ejido la Escondida cerro del gato, Ciudad Administrativa, 98160 Zacatecas, México, Departamento de Ingeniería en Metalurgia y Materiales, Instituto Politécnico Nacional – Escuela Superior de Ingeniería Química e Industrias Extractivas (ESIQIE), UPALM, 07051, Ciudad de México, México, Instituto de Investigaciones en Materiales, UNAM, Circuito exterior s/n. Cd. Universitaria, 04510 Ciudad de México, México