Dense Nb2AlC ceramic was synthesized from NbC, Nb, and Al powder mixture at 1650°C and a pressure of 30 MPa for 90 min using an in situ reaction/hot-pressing method. The reaction kinetics, microstructure, physical, and mechanical properties of the fabricated material were investigated. A thermal expansion coefficient of ∼8.1 × 10−6 K−1 was measured in the temperature range of 30°–1050°C. At room temperature a thermal conductivity of ∼20 W·(m·K)−1 and a Vickers hardness of ∼4.5 GPa were determined. The material attained Young's modulus, four-point bending strength and fracture toughness of ∼294 GPa, ∼443 MPa, and ∼5.9 MPa·m1/2, respectively. The nanolayered grains with a mean grain size of 17 m contributed to the damage tolerance of this ceramic. Quenching from 600°, 800°, and 1000°C into water at room temperature resulted in decrease in bending strength from 443 MPa for the as-synthesized Nb2AlC to 391, 156, and 149 MPa, respectively.
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Document Type: Research Article
Department of Materials and Science, University of Erlangen-Nuremberg, D-91058 Erlangen, Germany
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Publication date: October 1, 2009