Microstructure And Mechanical Properties Of Aluminium Alloy Produced From Recycled Beverage Cans

Aluminum is the most ubiquitous metallic material on earth. Considering its good mechanical, electrical and thermal properties in regard with a low specific mass it has become a key material in many fields such as transport and building. Light weighted, resistant to corrosion, and easily formed aluminum truly suits as well food packaging. Among the 210 billion beverage cans produced every year worldwide, 85% are made out of aluminum. The recycling industry of this metal, currently based on remelting, plays a leading role in North America, Europe and Japan and the activity is quickly increasing in China, India and Russia. Indeed, it requires 20 time less energy to recycle a can than producing the same amount of primary metal and the ratio is the same in terms of greenhouse gases emissions. In addition, aluminum cans are 100% recyclable and the material does not lose its properties during the process.The main goal of this thesis is focused on the study of the characteristics of aluminum alloy produced by mechanical milling and mechanical alloying using recycle beverage cans as a raw material. This process is not currently used in the industry in this purpose, and it could be an interesting alternative to remelting. Thus the objective of this project was to study nanostructured aluminum alloy powders and aluminum alloy matrix nanocomposite powders obtained by solid state process. Then the microstructure and the mechanical properties of these powders after consolidation were investigated. Trying to achieve efficient HEMM sets of parameters in order to process powder first form the aluminum alloy of the can alone and then plus an addition of nano silicon carbides reinforcement particles, we ended up with four different powders, resulting from the two compositions and two milling times. The characterization of these powders in terms of mechanical properties, microstructures and compositions was performed through Vickers hardness testing, ICP and XRD analysis, particle size measurement and SEM imaging. Concerning the micro-hardness of the powders, both a longer milling time and an addition of 5%Si C particles were associated with higher values. Through ICP-analysis of the raw material from the can and the powders and a comparison with a theorical composition of the processed material, the verification was done that a new alloy had been successfully achieved through HEMM from the mixing of the two alloys composing the can. The powders were consolidated through two ways and hot-extruded. An important tensile strength was achieved through both processes with values ranging between 600 MPa and 750 MPa. In spite of an increase of the plastic domain for SPS samples compare to cold-compacted ones, a better elongation was not noticed and the values went from 1.5% to 3%. The addition of 5%Si C, even though did not influence the hardness, led to an increase in the tensile strength. Moreover, iron particles were observed within the aluminum matrix which may influence the tensile strength and may crucially influence the failure of the material. The purpose of this study is to investigate the mechanical properties and microstructure of the powders processed by mechanical alloying using aluminum recycled cans as a raw material and of the extruded-bars obtained after consolidation.