Effect of tantalum solid solution additions on the mechanical behavior of ZrB2

Mechanical properties and microstructure were compared for zirconium diboride two solid solutions containing 3 6 at% tantalum diboride. X-ray diffraction indicated that the ceramics nearly phase-pure dissolved into ZrB2 lattice to form (Zr,Ta)B2 solutions. Microstructural analysis samples achieved full relative density with average grain sizes ranged from 3−5 μm. The three compositions had similar values of Young’s modulus (510−531 GPa), shear (225−228 Vickers hardness (15.2–16.4 flexural strength (391−452 MPa). Fracture toughness 2.6 3.7 MPa m1/2 increasing content, fracture mode changed predominantly intergranular transgranular. Diboride solution materials comparable single metal diboride, but differences in microstructure, secondary phases, strain state among partially obscured actual effects on behavior.