Rapid synthesis of highly pure Nb2AlC using the spark plasma sintering technique

In this work, highly pure Nb2AlC was successfully synthesized using the spark plasma sintering (SPS) technique with Nb, NbC and black carbon as raw materials at 1450 °C and 30 MPa for 8 min. The obtained Nb2AlC grain shows a characteristic layered structure. More interestingly, the obtained Nb2AlC exhibits good electrical, thermal and mechanical properties. The coefficient of thermal expansion is 9.0 × 10−6 K−1 from room temperature to 1200 °C. The electrical conductivity reaches 1.3 × 106 S m-1 at 500 °C, indicating excellent high-temperature conductivity. The Vickers hardness and flexural strength are 4.0 GPa and 440 ± 10 MPa, respectively. Importantly, fracture toughness of the obtained Nb2AlC material reaches 7.8 ± 0.2 MPa m1/2, which is higher than that of other previously studied MAX materials. Therefore, SPS is a very effective method to fabricate Nb2AlC materials and can also be used to prepare other MAX materials.