Research Projects

Metals and alloys are often claimed to be fully recyclable in the sense that they can be recollected, sorted, and remelted into new products. The constraint of making new alloys from scraps or mixing of scraps with primary metals affects recycling due to the aggregation of unwanted contaminants. The impurity elements assist the formation of intermetallic phases due to their low solubility in aluminium. These phases can affect fluidity, age-hardening behaviour, strength, elongation, fatigue, and corrosion behaviour of aluminium alloys. For example, Fe in aluminium alloys forms Al13Fe4 intermetallic phase, which is morphologically unfavorable. In practice, metallic scrap often consists of a mixture of different grades due to improper, unorganized sorting and storing systems. This leads to composition malice from that of the desired product composition. The major obstacles faced by the aluminium recycling industries are: (i) wide variety of scrap quality differ by product, composition and region, (ii) high strength/high performance aluminium alloys with no or little acceptance for impurity elements. Depending upon the scrap quality, solutions in most cases are (i) the use of aluminium scrap as a dilution (sweetening) to the primary aluminium, and (ii) recycling of aluminium scraps into lower value products (e.g., aluminium utensils and pots), where the property requirements are not so stringent. These solutions demonstrate a low recycling rate as a result of composition-specific ceilings and negative economic effects due to the production of lower-value products. The present proposal approaches to develop aluminium alloys with high scrap-related impurity tolerance, optimized casting, solutionizing, and heat treatment processes to regulate the detrimental effects of intermetallic phases and impurity elements. Aluminium scraps will be collected from the local dismantling unit and scrap sorting unit (End of life vehicles and Solar power plants waste). Based on the observed composition, the possible nearest engineering aluminum alloy will be identified and further tuning in the composition will be done by alloying. Melt cleanliness will be studied using reduced pressure test and K-mold. Aluminium alloy plates/ingot will be cast using gravity die casting, squeeze casting, and direct chill casting techniques. The recycled aluminium plates will further be homogenized, rolled and forged to control grain size and distribution of detrimental intermetallic phases. The performance evaluation will be done using mechanical tests. The recycled aluminium alloy be characterized using X-ray radiography to evaluate the presence of gas holes, shrinkage and foreign elements. Near-net shape casting will be performed to reduce the composition gradient, segregation, high dispersion of impurity-affected precipitates, and grain sizes. The self-piercing riveting feasibility of the cold-rolled aluminium plates will be performed to meet the industrial joining requirements.