Fabrication of Al-TiAl₃ Composite Via In-Situ Accumulative Roll Bonding (ARB) and Annealing

Abstract

In this study, titanium particles (with an average size of 48 µm) are dispersed throughout Al foils using the accumulative roll bonding method. The reaction between the particles and the matrix is subsequently activated thermally by post-rolling annealing. The in-situ reaction between the titanium powder and the aluminum matrix promoted by mechanical activation due to accumulative roll bonding and thermal activation due to annealing leads to the formation of Ti-Al intermetallic compounds. The distribution of particles and the intermetallic compounds thus formed are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission SEM (FESEM), electron probe micro-analysis (EPMA), and optical microscopy. The composite produced with 5 wt pct particles after 20 cycles of rolling and annealing yields the best particle distribution and TiAl₃ formation such that the only intermetallic compound formed is TiAl₃. The highest TiAl₃ contents are recorded in the Al-TiAl₃ composite formed by 20 cycles of rolling and annealed after rolling cycle numbers 5 and 9 (2 hours at 430 °C), as well as 12, 17, and 20 (2 hours at 600 °C). Surface energy is found to decrease when the most faceted particles become spherical in shape at high temperatures during the annealing process. Particles as small as 250 nm in size are also observed to form in this composite, and thus fabricated.