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The development of new low‐carbon emission methods for the synthesis and processing of materials is an urgent task today. Here, we present a rapid, efficient, and low‐energy‐consuming synthesis method for high‐yield Ti3AlC2 MAX phase powders. Our method is based on induction heating‐assisted combustion synthesis (IH‐CS), where the heat of the reaction is used as a driving force of the process, and the conditions of the process are finely controlled using IH at the same time. Ti3AlC2 MAX phase was synthesized using TiC0.67 and Al powders as starting materials. The introduction of TiC0.67 reduced the total exothermic effect of the reaction, facilitating better control of the reaction process. IH was used to ignite the reaction and to hold the temperature after ignition at an optimal value to complete the synthesis process. The effects of holding temperature, Al, and Si addition on Ti3AlC2 yield were investigated. As a result, Ti3AlC2 MAX phase powders containing only.7 wt% of the secondary phase were synthesized in a very short time. Our findings suggest that IH‐CS is a highly effective and promising alternative for the facile fabrication of high‐purity MAX phase powders. [ABSTRACT FROM AUTHOR]

Aluminium 6061 has a widespread applications in the automotive and aerospace sectors. However, because of its poor tribological properties, its life is limited. In this investigation, a surface composite of Ti 3 AlC 2 and Al 6061 alloy was prepared using friction stir processing and its effects have been studied. The examination of microstructure of the fabricated samples were studied using optical microscopy and scanning electron microscopy. The microstructural analysis revealed reduction in grain size within both the base metal FSPed and aluminium- Ti 3 AlC 2 composites. The area mapping showed uniform dispersion of Ti 3 AlC 2 particles within the friction stir processed zone. The microstructure refinement lead to increase in the microhardness. The average microhardness of the base metal was 65 HV 0.2 and that of base metal FSPed and Al- Ti 3 AlC 2 were 85 HV 0.2 and 135 HV 0.2. The grain refinement and uniform distribution of particles were found responsible for the improvement in wear properties. It was observed that the wear resistance improvement of more than 100% in comparison to the parent metal. The predominant wear mechanism, as demonstrated by scanning electron microscopy micrographs, was abrasive wear with varying degrees and features. [ABSTRACT FROM AUTHOR]

Ti3AlC2 is electrochemically synthesized from titanium‐rich slag/Al2O3/C mixtures in molten salts. The intermediate products are systematically analyzed to investigate the formation process of Ti3AlC2. The results show that the synthesis process typically involves an electrodeoxidation process and in situ carburization/combination process. In addition, most of the undesired metallic oxides contained in the titanium‐rich slag are removed effectively during the electrolysis process, and the removal mechanism of these undesired metallic oxides is further discussed. The influences of different molten salts (including molten CaCl2 and CaCl2–NaCl) and temperatures (range of 800–1000 °C) on the final products are also studied. The results show that these electrosynthesis conditions influence the morphology and phase composition of the products. The synthesized Ti3AlC2 particles possess an irregular plate‐like morphology. It is suggested that the molten salt electrochemical synthesis technology is a promising process to produce Ti3AlC2 and/or other MAX phases from multicomponent complex ores. [ABSTRACT FROM AUTHOR]

MAX phases are appropriate protective coatings due to their unique properties such as excellent corrosion resistance. In this study, Ti–Al–C coatings with different percentages of Ti, Al and C were deposited on stainless steel and quartz glass substrates by Arc-PVD using two different Ti–Al alloy targets with (1:1) and (1:2) atomic ratios in C 2 H 2 /Ar atmosphere with various ratios (1/10, 1/4, 1/2). Then, the coated substrates were annealed in a vacuum furnace at different temperatures between 600 and 1000 °C. The results of XRD analysis indicated that Ti 2 AlC MAX phase is generated from 1Ti–2Al target, while Ti 2 AlC and Ti 3 AlC 2 MAX phases are produced from 1Ti–1Al target by annealing at temperatures above 800 °C. Based on the results of this study, the best C 2 H 2 /Ar ratio in the Arc-PVD atmosphere for the synthesis of MAX phases was 1/4. Raman spectroscopy and XPS confirmed the presence of the MAX phases in the coatings. EDS analysis showed that the overall compositions occur within the regions in the ternary phase diagram in which the MAX phases are stable. [ABSTRACT FROM AUTHOR]

The work concerns the characterization of polycrystalline materials composed in Ti–Al–C system such as Ti2AlC and Ti3AlC2. The starting powders were synthesized from metal powder in nitrogen overpressure with the use of SHS method. Such obtained powders were chemically described and hot-pressed at temperatures 1100 °C and 1300 °C. The densification measurements were taken on obtained sintered bodies. The chemical composition analysis and microstructural observation of hot-pressed materials were made. The obtained MAX phase Young's modulus was examined in the temperature range 25–600 °C by resonance method. The thermal properties of the thermogravimetric analysis were made in air flow to determine the oxygen resistance. The MAX phase polycrystals were taken under laser flash analysis, which allowed to measure directly thermal diffusivity and specific heat and to calculate indirectly thermal conductivity up to the temperature of 700 °C. Additionally, the polycrystalline material was laser treated in continuous work mode. The hot-pressed MAX nanolaminates were laser ablation and laser welding processed, which is new in the literature. The laser beam-treated material places were microstructurally investigated by scanning electron microscopy and chemically by energy-dispersive X-ray spectroscopy. The result of laser processing was discussed regarding material preparation route and its thermal properties. [ABSTRACT FROM AUTHOR]

Authors present results of works on the interesting new group of advanced ceramics called MAX phases – Ti-based ternary carbides and nitrides. They have an original layered structure involved highly anisotropic properties laying between ceramics and metals, with high elastic modulus, low hardness, very high fracture toughness and high electrical and heat conductivity. Using Self-Propagating High-Temperature Synthesis (SHS) in the combustion regime it is possible to prepare MAX phases-rich powders that can be used as the precursors for preparation of dense MAX polycrystals by presureless sintering or hot-pressing. Different novel Ti-based phases with layered structures, namely: Ti3AlC2 and Ti2AlC have been synthesized in a combustion regime. The possibility of controlling of combustion phenomena for obtaining near single-phase products is discussed in details as well as some of properties of the materials tested as structure and functional ceramics.

The high specific surface area of multilayered two-dimensional carbides called MXenes, is a critical feature for their use in energy storage systems, especially supercapacitors. Therefore, the possibility of controlling this parameter is highly desired. This work presents the results of the influence of oxygen concentration during Ti3AlC2 ternary carbide—MAX phase preparation on α-Al2O3 particles content, and thus the porosity and specific surface area of the Ti3C2Tx MXenes. In this research, three different Ti3AlC2 samples were prepared, based on TiC-Ti2AlC powder mixtures, which were conditioned and cold pressed in argon, air and oxygen filled glove-boxes. As-prepared pellets were sintered, ground, sieved and etched using hydrofluoric acid. The MAX phase and MXene samples were analyzed using scanning electron microscopy and X-ray diffraction. The influence of the oxygen concentration on the MXene structures was confirmed by Brunauer-Emmett-Teller surface area determination. It was found that oxygen concentration plays an important role in the formation of α-Al2O3 inclusions between MAX phase layers. The mortar grinding of the MAX phase powder and subsequent MXene fabrication process released the α-Al2O3 impurities, which led to the formation of the porous MXene structures. However, some non-porous α-Al2O3 particles remained inside the MXene structures. Those particles were found ingrown and irremovable, and thus decreased the MXene specific surface area.

Ab inito calculations have been carried out to investigate the structure, phase stability, elastic and electronic properties of the solid solution of Ti3AlC2− xN x ( x = 0-2), which were compared with the isostructural and already synthesized end member Ti3AlC2. The substitution of C atoms by N atoms affects the structural parameters a and c. The differences of atomic radius and the bond lengths lead to the changes of structural parameters. Results indicate that Ti3AlCN has the lowest formation energy among the solid solutions, and from the calculation of the cohesive energy, it is found that the stabilities of Ti3AlC2− xN x ( x = 0-2) decrease as more N atoms substitute C atoms. The elastic moduli increase as more C atoms are replaced with N atoms. As x increases, Ti3AlC2− xN x solid solutions become stiffer than Ti3AlC2. The calculated density of states suggests that the conductivity of Ti3AlC2− xN x originates from the Ti-3 d contribution and the electrical conductivity becomes higher as more N atoms substitute C atoms. [ABSTRACT FROM AUTHOR]

Optimizing the hot working parameters of metal matrix composites is beneficial for improving the microstructure of the matrix and the distribution of the reinforcements and eliminating materials defects. In this work, the hot deformation behaviors of the 20 vol% flaky Ti 3 AlC 2 particles reinforced pure Al composite at strain rates of 10−3–1 s−1 and temperatures of 350–500 °C were investigated by hot compression tests. Friction correction equations were used to correct the flow stress data. The constitutive equations and processing maps were successfully established. The flow stresses of the Ti 3 AlC 2 /Al composite were precisely described through the hyperbolic sine constitutive equation. The true stress exponent was calculated to be 8, similar to the creep process with invariant microstructure. The particle rotation caused by the deformation of the Al matrix led to the alignment of the Ti 3 AlC 2 flakes. The optimum hot working parameters of the composite are in the range of 410–500 °C, 0.18–1 s−1 based on the processing maps. Dynamic recrystallization (DRX) had a higher proportion in the optimum safe region. The high temperature-low strain rate unstable region was associated with superplastic. The instability in the low temperature-low strain rate region stemmed from the interface microcracks generated by the rotation of Ti 3 AlC 2 flakes. The processing map theory can be well correlated with the microstructure evolution of the composite under different deformation parameters. • Hot deformation behavior of the 20 vol% Ti 3 AlC 2 /Al composite was investigated by hot compression tests. • Constitutive equation and processing maps were constructed based on the friction corrected flow stresses. • Perfect alignment of Ti 3 AlC 2 flakes was achieved in the high strain area of the sample. • Dynamic recrystallization (DRX) occurred at the high temperature-high strain rate region. [ABSTRACT FROM AUTHOR]

In moving towards a greener global energy supply, hydrogen fuel cells are expected to play an increasingly significant role. New catalyst support materials are being sought with increased durability. MAX phases show promise as support materials due to their unique properties. The layered structure gives rise to various potential (001) surfaces. DFT is used to determine the most stable (001) surface terminations of Ti2AlC, Ti3AlC2 and Ti3SiC2. The electrical resistivities calculated using BoltzTraP2 show good agreement with the experimental values, with resistivities of 0.460 µ Ω m for Ti2AlC, 0.370 µ Ω m for Ti3AlC2 and 0.268 µ Ω m for Ti3SiC2. Surfaces with Al or Si at the surface and the corresponding Ti surface show the lowest cleavage energy of the different (001) surfaces. MAX phases could therefore be used as electrocatalyst support materials, with Ti3SiC2 showing the greatest potential. [ABSTRACT FROM AUTHOR]

The high specific surface area of multilayered two-dimensional carbides called MXenes, is a critical feature for their use in energy storage systems, especially supercapacitors. Therefore, the possibility of controlling this parameter is highly desired. This work presents the results of the influence of oxygen concentration during Ti3AlC2 ternary carbide—MAX phase preparation on α-Al2O3 particles content, and thus the porosity and specific surface area of the Ti3C2Tx MXenes. In this research, three different Ti3AlC2 samples were prepared, based on TiC-Ti2AlC powder mixtures, which were conditioned and cold pressed in argon, air and oxygen filled glove-boxes. As-prepared pellets were sintered, ground, sieved and etched using hydrofluoric acid. The MAX phase and MXene samples were analyzed using scanning electron microscopy and X-ray diffraction. The influence of the oxygen concentration on the MXene structures was confirmed by Brunauer-Emmett-Teller surface area determination. It was found that oxygen concentration plays an important role in the formation of α-Al2O3 inclusions between MAX phase layers. The mortar grinding of the MAX phase powder and subsequent MXene fabrication process released the α-Al2O3 impurities, which led to the formation of the porous MXene structures. However, some non-porous α-Al2O3 particles remained inside the MXene structures. Those particles were found ingrown and irremovable, and thus decreased the MXene specific surface area. [ABSTRACT FROM AUTHOR]