Abstract
The purpose of the study was to establish how doping with various X elements affects the microstructural evolution of Ti-based MAX-phase alloys and how these changes affect hardness, thermophysical and tribological properties. The methodology provided for obtaining the base and doped series of Ti-Al-C alloys and their study by X-ray phase analysis, scanning electron microscopy, energy dispersion analysis, digital morphometry, microindentation, resonance determination of elastic modulus, dilatometry, thermogravimetric analysis, tribological tests, and statistical data processing. As a result, it was found that the base series retains the dominance of Ti₃AlC₂ at 87% and is characterised by the most ordered lamellar microstructure with an average grain size of 8.3 µm. Iron doping reduces the proportion of Ti₃AlC₂ to 62%, increases the TiC content to 28%, and is accompanied by the appearance of Fe₃Al, grain grinding to 5.7 µm, violation of the lamellar architecture, and the development of a heterogeneous carbide-intermetallic ensemble. This provides a maximum microhardness of 5.1 GPa, but simultaneously leads to a decrease in the elastic modulus to 191 GPa, density to 4.17 g/cm³, electrical conductivity to 2.1×10⁴ S/m, an increase in the coefficient of linear thermal expansion to 9.7×10-6 1/°C, mass loss according to the results of thermogravimetric analysis to 8.6%, and the worst tribological indicators. Silicon doping preserves Ti₃AlC₂ at 74%, is accompanied by the formation of Ti₅Si₃, supports a more ordered intergranular organisation with an average grain size of 6.9 µm and forms the most balanced complex of properties: microhardness 4.2 GPa, modulus of elasticity 214 GPa, density 4.44 g/cm³, electrical conductivity 3.2×10⁴ S/m, coefficient of linear thermal expansion 7.5×10⁻⁶ 1/°C, mass loss according to the results of thermogravimetric analysis – 3.4%, mass loss at friction – 3.4%, wear – 0.28 C.U., and the coefficient of friction – 0.47. The practical significance of the results lies in the possibility of their use in the development and selection of wear-resistant Ti-based MAX materials and coatings for drilling and oil and gas production equipment