Intermetallic Phase Control in Cast Aluminum Alloys by Utilizing Heterogeneous Nucleation on Oxides

With the increasing demand for premium-quality aluminum alloy castings that can be used as safety-critical structural components, as well as the rising urge to utilize sustainable materials during the manufacturing process, novel technologies need to be developed and implemented during the treatment of liquid alloys. Impurity and alloying elements accumulate in recycled aluminum alloys, which frequently results in the formation of coarse intermetallic compound (IMC) particles in the microstructure that have a detrimental effect on the ductility of cast products. One successful approach to alleviate this negative effect relies on affecting the phase selection and refinement of IMC phases. A growing body of literature has shown that the crystallization process of IMCs is affected by the native oxide phases present in the liquid alloys. It has also been demonstrated that by appropriate technologies, harmful oxide inclusion (like oxide bifilms) can be transformed into small-sized oxide particles that can be dispersed throughout the liquid alloy to serve as heterogeneous nucleation sites for different phases. In this way, the adverse effects of oxide inclusions and IMCs are simultaneously mitigated. This contribution aims to review the recent progress of experimental and theoretical work related to intermetallic particle refinement by oxide phases. Emerging technological solutions capable of refining intermetallics through transforming harmful oxide inclusions into numerous, well-dispersed heterogeneous nucleation sites are comprehensively reviewed. Besides analyzing the current state of these techniques, this discussion evaluates their future implications and the potential challenges that may arise in their application and development.