Innovative study and analysis on MAX phase (Ti3AlC2) A-layer atom solid solution with potential A site doped elements

Abstract

“Ti3AlC2, a member of the Mn+1AXn ceramic phases, demonstrates outstanding oxidation resistance, high specific stiffness, excellent corrosion resistance, and thermal conductivity. This research delves into the A-site solid-solution treatment of Ti3AlC2, with a specific focus on 18 elements derived from the main and subgroups of the periodic table. These elements, such as Pb, As, Si, S, Sb, P, Ir, Ge, Sn, Fe, Au, Co, Cu, Ni, In, Zn, and Ga, are all considered potential candidates for the A site.The enthalpies of formation of the Ti3(Al0.5A0.5)C2 compounds were determined to be negative, suggesting that these compounds can be synthesized through exothermic reactions. This finding highlights the improved formation capability when a specific A atom substitutes for an Al atom. Notably, Ti3(Al0.5Ir0.5)C2 exhibited the highest formation efficiency, as evidenced by its significantly higher absolute value of heat of formation compared to the other compounds.The electronic structures of all the compounds indicated that the energy bands became broader and showed improved electrical conductivity when the active element replaced the Al atomic position. In particular, the substitution of Al atomic positions in Ti3AlC2 with main group elements such as Si, Ge, and As, as well as B group elements such as Fe, Co, and Ir, leads to the formation of stronger bonds between Ti atoms, thereby creating a more stable structure.The substitution of Al atoms with Si, Ge, As, Fe, Co, and Ir atoms in Ti3(Al0.5A0.5)C2 was found to improve the resistance of the material to compressive deformation. This substitution also resulted in a decrease in the hardness of the Ti3AlC2 ceramic material but enhanced its ductility.