Fracture toughness determination and microstructure investigation of a B4C–NanoTiB2 composite with various volume percent of Fe and Ni additives

• We mixed a B4C with 10 vol.% of TiB2 and various values of iron or nickel additive.
• Sintering of the nanocomposite pieces was performed at 2400 °C under argon atmosphere.
• Increased use of Fe and Ni causes sinterability improvement and porosity reduction.
• The addition of nickel is seen to have a greater effect than the addition of iron.
• FeB and Ni3B blades were formed in the area between the B4C and TiB2 phases.

Boron carbide (B4C) has wide application in manufacturing of abrasives and cutting tools, due to its unique features such as high hardness, good wear resistance, low specific weight and chemical stability. An additive reinforcing phase and sintering aids are used to improve its sinterability. In the present paper, a B4C composite with 10 vol.% of titanium diboride nanoparticles (TiB2) and a 0, 1.5 and 2.5 vol.% iron or nickel metallic additive, respectively, was mixed in an isopropanol environment containing tungsten carbide pellets. After drying, the obtained mixture was formed by cold pressing. The obtained parts were sintered at 2400 °C. The effect of adding metallic sintering aids on the mechanical properties and microstructure of the composite was investigated and fracture toughness values were evaluated by indentation test method. Addition of Fe and Ni improved values for density, hardness, Young’s modulus and fracture toughness, with Ni addition increasing the values considerably. Scanning electron microscope (SEM) images of the microstructure of the specimens showed the arrangement posture of the additives and confirmed the results obtained. Additionally, the FeB and Ni3B blades formation were observed from the images.