Effect of Ti content and stirring time on microstructure and mechanical behavior of Al-B4C composites

• Tri-modal Al-B4C-Al3Ti composites were successfully fabricated by conventional stir casting technique.
• Ti content and stirring time effect were systematically investigated.
• Fracture behavior of Al-B4C interface were characterized.

Ti content and stirring time are two important parameters of stir casting technique for Al-B4C composites. In this study, their effect on microstructure and mechanical behavior of Al-B4C composites were investigated. A simple way to fabricate tri-modal Al-B4C-Al3Ti composites was proposed and efforts have been made to correlate microstructure evolution with mechanical response of the composites. It was found that, higher Ti levels resulted in higher volume fraction and particle size of Al3Ti, denser TiB2 interface and even more uniform spatial distribution of B4C. A prolonged stirring time, led to copious coarse TiB2 crystals at the expense of Al3Ti particles and generally more homogeneous spatial arrangement of particles. As a result, their tensile strength showed an inclined leaf-shape curve. These observations were interpreted in terms of synergy of Al3Ti particles, uniformity of particle spatial distribution, coarse TiB2 crystals and Al-B4C interface.