Fabrication, Microstructure, and Mechanical Properties of Tip/Al Composite

Abstract

The demand for advanced materials in modern industry and technologies is increasing, because pure metals and simple alloys can not meet the needs of society. Metal matrix composites (MMCs) are advanced materials that have been one of the hot fields of materials research. [1,2] MMCs, especially aluminum-and titanium-based materials, have a high potential for advanced structural applications in which high specific strength and modulus, as well as good elevated-temperature resistance, are important. Particulatereinforced MMCs are of special interest because of their ease of fabrication, low cost, and more isotropic properties. The properties of MMCs are controlled by the size and volume fraction of the reinforcement phase as well as by the nature of the matrix±reinforcement interface: an optimum set of mechanical properties tends to be obtained when fine and thermally stable ceramic particulates are dispersed in a metal matrix.Traditionally, MMCs have been produced by processing techniques such as powder metallurgy, [1,2] preform infiltration, [3] spray deposition, mechanical alloying, and various casting technologies, such as squeeze casting, rheocasting, and compocasting. [4±8] Such methods are based on the addition of the particulate reinforcement to the matrix material in molten or power form. The scale of the reinforcing phase is limited by the starting-power size, which is typically of the order of microns to tens of microns, and rarely less than 1 lm.In traditional MMC processing it is often necessary to improve the wetting between the molten metal and the particulate (which is typically poor) in order to obtain a good bond between the matrix and reinforcement. This problem can be resolved by adding a strongly reactive alloying element such as Mg or Li, or by coating the particulate. Mechanical stirring or pressure infiltration can also be helpful. Other difficulties, such as uneven distribution of reinforcements, interfacial reactions between the matrix and reinforcements, and control of volume fraction are often encountered during the fabrication of MMCs. Such factors can adversely affect the properties of the product.In recent years, new processing techniques based on in situ production of MMCs have emerged. In situ techniques involve a chemical reaction resulting in the formation of a very fine and thermodynamically stable reinforcing ceramic phase within a metal matrix. As a result, this provides thermodynamic compatibility at the matrix±reinforcement interface. The reinforcement surfaces are also likely to be free of contamination and, therefore, a stronger matrix±dispersion bond can be achieved. Some of these technologies include DIMOX TM , XD, PRIMEM TM , reactive gas infiltration, hightemperature self-propagating synthesis (SHS), liquid±solid or solid±gas±liquid reactions, [9±14] and plasma in situ MMCs. [15] Thus in situ composites are a new topic of interest in MMC research. They have some advantages over traditional MMCs, such as excellent interfacial bonding and easy production technology....

Novel Nanoparticle‐Reinforced Metal Matrix Composites with Enhanced Mechanical Properties

“…Apart from forming the in-situ ceramic particles, metallic and intermetalllic compound particles can also be induced in Albased alloys via exothermic reactions of constituent elements of materials. [33][34][35] Very few information is available in literature regarding the formation of in-situ nanoparticles in Albased alloys. Secondary processing technique such as friction stir processing (FSP) offer potential applications for forming in-situ nanoparticles and for achieving a uniform distribution of reinforcing particles in matrix of the composites.…”

Animal Origin Bioactive Hydroxyapatite Thin Films Synthesized by RF-Magnetron Sputtering on 3D Printed Cranial Implants

“…Ti6Al4V is the most popular titanium alloy used in biomedical applications due to its high strength, high fracture toughness, superior corrosion resistance, low density, excellent biocompatibility, and favorable osseointegration [1][2][3]. Even if Ti6Al4V is considered as a highly biocompatible metallic material, there have been reports of inflammatory reactions occurring around the prostheses upon implantation [4][5][6][7][8]. In order to improve the biocompatibility of the metallic alloys, a bioactive material can be deposited on its surface as a thin film, in order to increase the osseointegration and to ensure the biomimetism of the implant [9][10][11][12][13][14][15].…”