Investigation on the Microstructure and Tensile Properties of Al5083-TiB2 Nanocomposites Produced by Stir Casting Method

This study was conducted to investigate the effect of adding titanium diboride (TiB2) nanoparticles on the microstructure and tensile properties of the Al5083 matrix composite. Al5083/TiB2 metal matrix composites (with 5 and 10 wt % reinforcement) along with zirconium (Zr) and cerium oxide (CeO2) additives with different wt % were fabricated by in situ-stir casting at 1000 °C. The samples were then subjected to hot extrusion for uniform distribution of reinforcements in the matrix. TiB2 nanoparticles were in-situ processed in molten aluminum using the precursors such as cryolite (Na3AlF6), titanium oxide (TiO2), and potassium tetrafluoroborate (KBF4). The microstructure, surfaces, and failure mechanism of the samples were investigated using X-ray diffraction (XRD), optical microscopy (OM), and scanning electron microscopy (SEM). Tensile test results showed that the addition of 10 wt % TiB2 particles increased the ultimate tensile strength by 17.7 % and decreased the strain by 19.2 % compared to the sample without reinforcement. Besides, the addition of Zr and CeO2 increased the strength by 35.8 % and the strain of the sample containing 78 % by 10 % reinforcement compared to the sample without reinforcement due to the removal of intermetallic compound Al3Ti and the incompatibility between coefficients of thermal expansion (CTE) with the matrix. Also, post-extrusion annealing in the sample with 10 wt % TiB2 reduced the tensile strength.