A novel method for preparing graphene nanosheets/Al composites by accumulative extrusion-bonding process

Graphene nanosheets (GNSs) reinforced aluminium composite was fabricated from inexpensive graphite by a novel hot accumulative extrusion bonding (AEB) method with only three cycles. The microstructure, mechanical properties and electrical conductivity of composite were systematically researched to confirm the exfoliation of GNSs from graphite and reveal the exfoliation mechanism. Our study showed that GNSs with thickness about 10 nm were gradually exfoliated and the exfoliation came to an end at weak defective areas, such as vacancy, grain boundary. An ideal elastic modulus of GNSs/Al (∼80 GPa) was realized with 3-cycle AEB process. And a stabilized strain hardening stage was achieved with GNSs, even longer than its counterpart without GNSs. Meanwhile, the electrical conductivity of GNSs/6063Al with 2-cycle and 3-cycle AEB were 1% IACS higher than that of reference Al with the same preparation procedure. These results demonstrate that AEB is a promising method to prepare GNSs/Al composite economically and efficiently. This study can also provide new insights to the difference of strengthening and toughing mechanism between bulk graphite and graphene.