Fabrication of 6061Al–5 wt%TiB2 In Situ Composite Strips by Mixed Salt Method and Twin-Roll Casting

Abstract

6061Al–5 wt%TiB2 in situ composite strips were produced by a novel process. For comparison, the as-cast composites were prepared by the commonly used method and processed into strips. In the process, 6061Al–5 wt%TiB2 slurry was prepared by using the mixed salt method by making the molten Al react with stoichiometric mixed salts of KBF4 and K2TiF6. To fabricate the composite strips of as-cast state and cast-rolling state, the slurry of 50-min insulation was cast into a permanent mould and a twin-roll caster, respectively. Microstructures of both as-cast state and cast-rolling state were investigated by metallurgical microscope, X-ray diffraction, scanning electron microscope, and transmission electron microscope, and ultimate tensile tests were conducted to evaluate the mechanical properties thereof. The experimental results demonstrated that the twin-roll casting could significantly improve the microstructure and mechanical properties of the aluminium matrix composite strips. The microstructural improvement for the cast-rolling state was due to the quick cooling and deformation along the cast-rolling direction. The yield stress, the ultimate tensile strength, and the elongation of the cast-rolling state got improved by 67.9%, 31.9%, and 19.24%, respectively, compared with the as-cast state.