Production and characterization of spark plasma sintered (Ti,Nb)B₂ solid solutions with graphene nanoplatelets and hexagonal boron nitride

For this study, (Ti,Nb)B-2 solid solutions were consolidated by spark plasma sintering. In addition, (Ti,Nb)B-2 with graphene nanoplatelets (GNPs) and hexagonal boron nitride (h-BN) were produced to evaluate the potential of the new structural materials. The phase formation, microstructure, mechanical properties, oxidation resistance and room temperature reflectance, and absorbance features of (Ti,Nb)B2 were investigated. X-ray diffraction and Transmission electron microscopy observations showed that a complete solid solution phase was formed when the samples were sintered at 1850 degrees C for 5 min under 50 MPa. Ti0.75Nb0.25B2 exhibited a relative density of similar to 98.6%, a hardness of similar to 20.5 GPa, and an indentation fracture toughness of similar to 3.4 MPa center dot m(1/2). It was found that the presence of 1 vol% h-BN as an additive enhanced the hardness (-10%) and fracture toughness (similar to 30%) of Ti0.75Nb0.25B2 by activating toughening mechanisms. The GNP added Ti0.75Nb0.25B2 proved to have better oxidation resistance and optical absorbance than the other materials used in the study.