Synthesis. Nb2AlC MAX phase was prepared as described per Naguib et al. Elemental powders of niobium (99.9% metals basis, 325 mesh), aluminum (99.8% purity, 300 mesh), and carbon black (99% purity, 300 mesh) were mixed in a plastic jar with a ratio of 2:1.1:1 Nb:Al:C and ball milled. The powder was placed into an alumina boat and heated under Ar flow to 1600 °C, with a ramp rate of 4 °C•min -1 , and sintered for 4 h. After natural cooling to room temperature, the MAX phase was milled into powder and sieved through a 400-mesh sieve.