Luke Wilson, “Effect of Cooling Rate on the Microstructure of Al-12Ce and Al-12Ce-2.5Mg-Ni-Graphite”
Mentor: Pradeep Rohatgi, Materials Science & Engineering, Engineering & Applied Science (College of)
Poster #38
Aluminum (Al) alloys are a desirable class of materials for lightweight structural or functional components but suffer from diminished strength at high temperatures. Cerium (Ce) as an alloying element in Al has been shown to drastically improve mechanical properties affected by temperature. The addition of nonmetallic reinforcements such as graphite can further augment properties of a casting in unique and useful ways. This study explores the impact of cooling rate variation on the microstructure and properties of an Al-12Ce-2.5Mg alloy reinforced with Ni-Graphite. Samples were fabricated via stir mixing and cast in a preheated permanent step mold with section sizes ranging from 3.75 mm to 30 mm. The distribution of graphite, primary and eutectic phases, hardness, and density were measured as functions of section size and cooling rate. Results demonstrate that the size of intermetallic phases and hardness vary significantly with cooling rate, revealing a strong dependence of mechanical properties on thermal conditions. Comparisons with the base Al-12Ce-2.5Mg alloy highlight the role of Ni-Graphite in modifying microstructure and properties under varying cooling rates. The study also identifies Ni-Graphite particles as nucleation sites for intermetallic phases, with Al11Ce3 transitioning from rod-like to angular structures as cooling rate increases. These findings underscore the potential of cooling rate and reinforcement type on the performance optimization of aluminum-based composites, particularly in high-temperature applications such as automotive and aerospace industries.