Abstract
The rapid obsolescence of electronic devices has led to an exponential increase in e-waste generation, creating a significant environmental concern. However, e-waste also represents a valuable source of secondary resources, containing significant quantities of metals, including those crucial for superalloy production. The recycling of electronic waste (e-waste) has gained significant attention as a sustainable solution to recover valuable materials while mitigating environmental pollution. The purpose of this study is to examine the casting of multicomponent superalloys from foundry returns alloyed with recovered e-waste, with an emphasis on the establishment of an optimised casting process and parameters to overcome the difficulties posed by contamination, solidification behaviour, and variability in material composition. Six different alloy compositions, three high in NiCrMo phase and three high in NiMo phase were investigated. Two reference samples from each category and free of e-waste were utilized as standards for comparison purposes. SEM-EDS, optical microscopy, XRD, XRF, and hardness tests were used collectively for a thorough assessment. The findings show that the addition of e-waste profoundly alters the microstructures, resulting in the formation of Cu-Sn and Ni-Sn intermetallic phases and Pb-rich inclusions, which are mostly found in interdendritic areas, phase segregation, and the creation of Cu-rich boundaries. The segregation found along grain boundaries might be due to Cu and Pb's affinity for these high-energy sites. The trend is that the precipitates are greater in the 6% e-waste alloyed samples than in the 3% e-waste alloyed samples. While XRD results verified the widening of diffraction peaks for alloys containing e-waste, which is suggestive of decreased phase stability, XRF results showed increased amounts of Cu, Sn, and Pb. Hardness tests showed that alloys alloyed with Cu-Sn-Pb e-waste had a substantial decline in hardness because of the impacts of impurity stresses and weaker grain boundaries, the highest hardness value recorded by the e-waste alloys is 323.6 ±16 HV. According to the study, high-performance alloy manufacturing has the potential for sustainable recycling solutions as long as impurity-induced problems are managed by optimal processing techniques. To enhance this sustainable material strategy, more research into mechanical performance, sophisticated processing, and practical validation are advised.