Reaction spark plasma sintering of niobium diboride

Niobium diboride (NbB2) is synthesized and consolidated by the spark plasma sintering technique. Elemental reactants such as niobium (Nb) and boron (B) were subjected to two stage heat treatment, initially at 1200 degrees C for synthesis and followed by densification at the temperatures in the range of 1700 degrees C to 1900 degrees C. High dense NbB2 (similar to 97.7%rho(th)) is obtained at 1900 degrees C after 15 min holding period. Load application during heat treatment stage is found to improve the sinterability of the niobium diboride compacts. Hardness, elastic modulus and indentation fracture toughness of the high dense NbB2 are measured as 20.25 GPa, 539 GPa and 4 MPa m(1/2) respectively. (C) 2013 Elsevier Ltd. All rights reserved.