The nucleation sequence of ?-Al on TiB2 particles in Al-Cu alloys

The refinement of Al alloys by TiB2 has been extensively investigated for decades, both in industry and academia. In order to achieve higher grain potency, it is known that other solutes must be added alongside TiB2, thus tailoring the heterogeneous nucleation at interface between particles matrix. Here, we report results from an atomic-scale experimental investigation Al-Cu based as well Al-5Ti-1B refiner employed these alloys. We focus on effect segregation main solute elements (Ti, Cu) attempt disentangle this factors affecting growth. Significant Ti form a Ti-rich layer, identified Al3Ti two-dimensional compound, was unambiguously observed basal plane refiner, agreement with prior literature. alloy system, prevalent also accompanied cases when Cu concentration high presence further Cu-rich layer. Based observations, possible sequence addition proposed whereby occurs layer surface which can then preserved subsequent peritectic transformation surrounding eutectic reaction forms sufficient present. This should help link absence or layers processing conditions post-solidification studies. Although difficult know absolute certainty if particle microstructure active inactive during solidification process, study highlights role refiner.