Microstructure and some properties of TiAl-Ti2AlC composites produced by reactive processing
TL;DR: In this paper, the composites with and without impurities, Ni, Cl and P, were prepared by combustion reaction from the elemental powders and cast after arc melting, and the resulting composites had about 18vol% Ti2AlC in the lamellar matrix consisting of -TiAl and Ti3Al (2).
About: This article is published in Intermetallics.The article was published on 1999-05-01. It has received 66 citations till now. The article focuses on the topics: Toughness & Fracture toughness.
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TL;DR: In this paper, the development trend of modification on high temperature oxidation resistance of titanium alloys and titanium aluminides in the future is forecasted, including whole alloying modification and surface modification.
325 citations
TL;DR: In this paper, the phase assemblages of the samples consisted of Cr2AlC, as a major crystalline phase, together with a very small amount of Cr7C3 and an unknown phase.
178 citations
TL;DR: In this article, the deformation of polycrystalline Ti2AlC under room and high temperature compression was investigated and the results demonstrated that the material was damage tolerant at room temperature and the samples were shear fractured upon failure.
Abstract: Deformation of polycrystalline Ti2AlC under room and high temperature compression was investigated. The results demonstrated that Ti2AlC was damage tolerant at room temperature and the samples were shear fractured upon failure. At high temperatures Ti2AlC deform plastically. The brittle-to-ductile-transition temperature (BDTT) of Ti2AlC was between 1000 °C and 1050 °C. The microstructure and fracture surfaces were examined using scanning electron microscopy. Due to insufficient number of dislocation systems, the room-temperature deformation was constitute of kinking and delaminating of laminated Ti2AlC grains, basal plane dislocation slip, formation of voids and cavities in the vicinity of main crack. At high temperatures below BDTT, the deformation was a combination of cavities formation and intergranular sliding. At temperatures above BDTT, the deformation was mainly plastic flow.
72 citations
TL;DR: In this article, the LENS process was employed to fabricate carbide-particle-reinforced titanium aluminide-matrix composites using TiC and gas-atomized Ti-48Al-2Cr-2Nb powders as the feedstock materials.
Abstract: TiAl-based titanium aluminide alloys and their composites reinforced with ceramic particles are considered to be important candidate materials for high-temperature structural applications. Laser-engineered net shaping (LENS) is a layered manufacturing process, which involves laser processing fine powders into three-dimensional components directly from a computer-aided design (CAD) model. In this work, the LENS process was employed to fabricate carbide-particle-reinforced titanium aluminide-matrix composites using TiC and gas-atomized Ti-48Al-2Cr-2Nb powders as the feedstock materials. The composites deposited by the LENS process were susceptible to solid-state cracking due to high thermal stresses. The microstructures of the laser-deposited monolithic and composite titanium aluminide materials were characterized using light optical microscopy (LOM), scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS) analysis, electron-probe microanalysis (EPMA), and X-ray diffraction (XRD) techniques. Effects of the LENS processing parameters on the cracking susceptibility and microstructure were studied. Crack-free deposits were fabricated by preheating the substrate to 450 °C to 500 °C during LENS processing. The fabricated composite deposits exhibit a hardness of more than twice the value of the Ti-6Al-4V alloy.
71 citations
10 Jan 2013-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the authors used the in situ method of combustion synthesis and hot press consolidation to construct a TiAl matrix composites reinforced with nano-TiB2 and nano-Si3 particles.
Abstract: The TiAl matrix composites reinforced with nano-TiB2 and nano-Ti5Si3 particles were successfully fabricated by the in situ method of combustion synthesis and hot press consolidation. The sizes of the synthesized TiB2 and Ti5Si3 particles are about 30–50 nm and 60–80 nm, respectively. The synthesized nano-TiB2 particles could significantly enhance the ultimate compression strength ( σ true UCS ) of the TiAl alloy, and the σ true UCS increases with the increase in the TiB2 content. The average σ true UCS of the 6 vol% TiB2/TiAl composite is 477 MPa higher than that of the TiAl alloy. The synthesized nano-Ti5Si3 particles could improve the strength and ductility of the TiAl alloy simultaneously, and the σ true UCS and fracture strain ( e t r u e f ) increase first and then decrease with the increase in the Ti5Si3 content. The average σ true UCS of the 4 vol% Ti5Si3/TiAl composite is 171 MPa higher than that of the TiAl alloy, and the average e t r u e f increases from 17.3% to 20.9%.
63 citations
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TL;DR: In this paper, an improved understanding of both fundamental and practical aspects of these aluminides, such as phase relations, microstructure evolution and control, processing, micro-structure-property relationships, and deformation and fracture processes, is presented.
Abstract: Extensive research during the last eight years has resulted in the development and improvement of second-generation gamma alloys of engineering importance, Ti-48Al-2(Cr or Mn)-2Nb and derivatives. These alloys exhibit properties, in duplex micro-structural forms, meeting requirements for some gas-turbine and automobile engine components that may be used up to 760 °C. These achievements were made possible by an improved understanding of both fundamental and practical aspects of these aluminides, such as phase relations, microstructure evolution and control, processing, microstructure-property relationships, and deformation and fracture processes. Nevertheless, widespread higher performance and/or higher-temperature applications of these alloys appear unlikely unless the current properties are dramatically improved.
722 citations
01 Jan 1989
379 citations
"Microstructure and some properties ..." refers methods in this paper
...To improve these properties, recently many composites have been studied with ductile particle reinforcements like -TiNb [3,4] and with brittle particle reinforcements TiB2 [5,6], Ti2AlC [7±11], Ti2AlN [12], TiB2+Ti2AlN [13] and TiB2+Ti2AlC [14]....
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...To improve these properties, recently many composites have been studied with ductile particle reinforcements like -TiNb [3,4] and with brittle particle reinforcements TiB2 [5,6], Ti2AlC [7±11], Ti2AlN [12], TiB2+Ti2AlN [13] and TiB2+Ti2AlC [14]....
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TL;DR: In this article, high temperature phase equilibria and microstructure evolution during solidification were investigated for Ti-Al alloys in the range 40-55 at.%Al.
366 citations
TL;DR: In this article, the authors present a review of intermetallic matrix composites (IMCs), concentrating on the last four years and drawing examples from the three most widely researched matrix systems: titanium aluminides, nickel aluminide and molybdenum disilicide.
292 citations
TL;DR: In this paper, a new class of oxidation-resistant coatings based on the Ti-Al-Cr system is proposed, which offers the potential for improved fatigue life for high temperature titanium alloys.
Abstract: The excellent density-specific properties of the gamma class of titanium aluminides make them attractive for intermediate-temperature (600–850 °C) aerospace applications. The oxidation and embrittlement resistance of these alloys is superior to that of the α2 and orthorhombic classes of titanium aluminides. However, since gamma alloys form an intermixed Al2O3TiO2 scale in air rather than the desired continuous Al2O3 scale, oxidation resistance is inadequate at the high end of this temperature range (i.e., greater than 750–800°C). For applications at such temperatures, an oxidation-resistant coating will be needed; however, a major drawback of the oxidation-resistant coatings currently available is severe degradation in fatigue life by the coating. A new class of oxidation-resistant coatings based in the Ti-Al-Cr system offers the potential for improved fatigue life.
179 citations