Investigating Mechanical Behavior of Al A356-B4C / TiB2 Composite Produced by Stir Casting

This study investigated the effect of adding boron carbide microparticles (B4C) and titanium diboride nanoparticles (TiB2) on the microstructure, tensile strength, and hardness of A356 aluminum composite. In so doing, 2.5, 5, and 7.5 vol.% B4C reinforcements and 2.5 vol.% TiB2 reinforcement were added to the field by stir casting at 1000 °C using in situ process. The TiB2 nanoparticles were processed in situ by cryolite precursors (Na3AlF6), titanium oxide (TiO2), and potassium tetrafluoroborate (KBF4) in aluminum melt, and B4C microparticles were added directly into the melt. X-ray diffraction (XRD), optical microscope (OM), and scanning electron microscope (SEM) were used to investigate the microstructure and failure mechanism of the samples. Also, hardness and tensile tests were carried out to test mechanical properties. The results showed that addition of B4C first decreased and then increased the ultimate tensile strength compared to the sample without reinforcement. Moreover, the highest value of tensile strength was for the sample containing 2.5 vol.% of B4C and 2.5 vol.% TiB2, which showed a 235% improvement compared to the sample without an amplifier. However, the tensile strength of the sample containing 2.5 vol.% of B4C was reduced by 35% compared to the sample without reinforcement. The results of the hardness test showed a drop in properties of the samples containing 2.5% of B4C reinforcement. the highest value of tensile strength was for the sample containing 2.5 vol.% of B4C and 2.5 vol.% TiB2, which showed a 33% improvement compared to the sample without reinforcement.