The Synthesis of Cast Materials Based on the MAX Phases in a Cr–Ti–Al–C System

Two variants of the self-propagating high-temperature synthesis (SHS) process, namely, SHS from elements and SHS metallurgy, are combined to obtain cast materials based on the Cr 2 AlC and (Cr 0.7 Ti 0.3 ) 2 AlC MAX phases. The experiments involve mixtures with the compositions calculated according to the chemical scheme 70% (Cr 2 O 3 + 3Al + C)/(2Ti + Al + C) + 30% (3CaO 2 + 2Al). The synthesis is carried out in a 3-L reactor at a pressure of argon of 5 MPa. The structure and phase composition of the reaction product are studied by X-ray diffraction and scanning electron microscopy. It is found during the research that the ratio of the initial reagents has a substantial effect on the synthesis parameters and phase composition of the desired products. The possibility of obtaining a cast material based on the titanium-doped Cr 2 AlC phase is shown. It is found that the product is a composite material based on the (Cr 1 – x Ti x ) 2 AlC ( x = 0.18–0.28) phase, the concentration of which is 43–62 wt % depending on the initial ratio of the reagents. The microstructure of the material is characterized by the presence of laminate layers with the inclusions of carbide grains. The end product contains carbide (Ti 0.9 Cr 0.1 C, Cr 7 C 3 , Cr 3 C 2 ) and intermetallic (Al 8 Cr 5 , AlTi 3 ) impurities, which is determined by the insufficient lifetime of the melt formed in the combustion wave.