A study of Ti3Al1−xSixC2 (x = 0 to x = 1) MAX-phase alloys is reported. The materials were obtained from mixtures of Ti3AlC2 and Ti3SiC2 powders with hot pressing sintering technique. They were characterised with X-ray diffraction, heat capacity, electrical resistivity, and magnetoresistance measurements. The results show a good quality crystal structure and metallic properties with high residual resistivity. The resistivity weakly varies with Si doping and shows a small, positive magnetoresistance effect. The magnetoresistance exhibits a quadratic dependence on the magnetic field, which indicates a dominant contribution from open electronic orbits. The Debye temperatures and Sommerfeld coefficient values derived from specific heat data show slight variations with Si content, with decreasing tendency for the former and an increase for the latter. Experimental results were supported by band structure calculations whose results are consistent with the experiment concerning specific heat, resistivity, and magnetoresistance measurements. In particular, they reveal that of the s-electrons at the Fermi level, those of Al and Si have prevailing density of states and, thus predominantly contribute to the metallic conductivity. This also shows that the high residual resistivity of the materials studied is an intrinsic effect, not due to defects of the crystal structure.
The work concerns the characterization of polycrystalline materials composed in Ti-Al-C system such as Ti 2 AlC and Ti 3 AlC 2 . 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 hotpressed 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.
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