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A group of MAX phases including Ti 2 AlC and Ti 2 AlN, are candidate reinforcements of Ag-based electrical contact materials. In this work, the interfacial reaction, resistivity, hardness and arc erosion resistance of Ag/Ti 2 AlX (X = C, N) were investigated comparatively. During the sintering of both Ag/Ti 2 AlX, Al deintercalated from Ti 2 AlX and Ag diffused into Ti 2 AlX. The interfacial reaction was mild in Ag/Ti 2 AlN while obvious in Ag/Ti 2 AlC. The first-principles calculation indicated that the higher vacancy formation energy of Al in Ti 2 AlN led to the mild reaction in Ag/Ti 2 AlN, which then resulted in a larger decrease in hardness and resistivity, as compared with Ag/Ti 2 AlC. Moreover, Ag/Ti 2 AlN showed superior arc erosion resistance, with less evaporation of Ag and oxidation of Ti 2 AlC. This were attributed to the lower vulnerability of mildly decomposed Ti 2 AlN, less resistance heat and easier heat dissipation, resulting from the superior electrical and thermal conductivity. • Interfacial reaction of Ag/Ti 2 AlX occurred by the diffusion of Ag into Ti 2 AlX and the outward diffusion of Al into Ag. • Higher vacancy formation energy of the Al of Ti 2 AlN contributed to less obvious interfacial reaction of Ag/Ti 2 AlN. • The interfacial reaction resulted in the increase of resistivity, and the stress relief led to the decline of hardness. • More intense reaction of Ag/Ti 2 AlC resulted in larger increase in resistivity and smaller decrease in hardness. • Mildly decomposed Ti 2 AlN and lower resistivity endowed the Ag/Ti 2 AlN with better arc erosion resistance. [ABSTRACT FROM AUTHOR]