Microstructure and mechanical properties of in-situ TiB2/Al composites

The in-situ TiB2/pure Al composites were fabricated successfully by titanium salt and boron salt reaction process. The influences of TiB2 contents (1%, 2% and 3%, mass fraction) on microstructure and mechanical properties were studied by scanning electronic microscopy, transmission electronic microscopy and tensile test machine. The results show that the morphologies of TiB2 particles present in rectangular, nearly rounded and hexagonal with the size of about 200-500 nm. And the interface between TiB2 particles and Al matrix is clean. Tensile test results indicate that the strength significantly increases while the elongation decreases with the increasing of TiB2 particles. The yield strength (YS) and ultimate tensile strength (UTS) of TiB2/pure Al composite at 3% TiB2 particles reach 78.1 MPa and 102 MPa, respectively, while the elongation reduces to 32.5%. The composite has achieved 58% and 43% improvement, respectively, in YS and UTS with respect to pure Al, while compromising 24% in ductility. The fractography reveals that agglomerations happen severely with increasing the TiB2 particles amounts, and the crack propagation tends to begin from the agglomerations, which leads to the decreasing of ductility. © 2020, Science Press. All right reserved.