RECYCLING OF ALUMINIUM MATRIX COMPOSITES (AMCS): A REVIEW AND THE WAY FORWARD

The present review paper mainly focuses on the modifications in the characteristics of Aluminium Matrix Composites (AMCs) after recycling. The recycling of AMCs is one of the major issues considering the increasing usage of AMCs. The recycling of AMCs is mainly performed through the removal or retention of particles and base alloy. The recycling of AMCs with particle removal involves mechanical, gravitational, pressure-driven and chemical methods. The major issues associated with particle removal techniques are reduced metal yield, wastage of particles and reduced purity of remaining host metal. Researchers observed that the maximum recovered metal yield is up to 60% and reinforcements cannot be utilized in the recovered form for further applications due to the presence of impurities and contaminations. The recycling of AMCs without separation involves direct remelting and casting. The major challenge in this method is the generation of detrimental intermetallics which are deteriorating the properties and quality of composites. The Al4C3 and MgAl2O4 phases are generated during remelting of SiC- and Al2O3-reinforced AMCs, respectively. The intermetallics are formed due to the chemical interactions between the reinforcements and liquid alloy or the specific elements present in the matrix during remelting of AMCs. The results revealed that the weight fraction of the generated intermetallics is gradually increased after each remelting. Moreover, the mechanical and tribological properties of AMCs are deteriorated after successive remelting due to the brittle nature of intermetallics. In order to overcome the challenges during recycling of AMCs, future research directions are also presented.

Automated summary

This review paper focuses on the modifications in the characteristics of Aluminium Matrix Composites (AMCs) after recycling. The recycling is mainly done through the removal or retention of particles and base alloy. The challenges include reduced metal yield, wastage of particles, and the generation of detrimental intermetallics.