Effect of Cr micro-alloying on microstructure and mechanical properties of alumina whisker and graphene co-reinforced copper matrix composites

Abstract

This work attempted to strengthen the interfacial strength and mechanical properties of alumina whisker and graphene co-reinforced copper matrix composites by Cr matrix micro-alloying. Cr elements are observed to: (i) aggregate to form large particles rather than disperse uniformly in Cu matrix; (ii) disperse at interfaces between Cu matrix and reinforcements. The relative density, tensile strength, shear strength and compressive strength of the Cu-Cr composites were in direct proportional to Cr micro-alloying amount from 0 to 1.5 wt%. Increased Cr micro-alloying amount, on the one hand, can strengthen interfacial bonding between Cu matrix and reinforcements and thereby enhance the load transfer efficiency at interfaces; on the other hand, can yield obvious grain refinement, and thereby achieving grain boundary strengthening as well as twin boundary strengthening, which were considered as the dominant strengthening mechanisms of Cu-Cr composites. Besides, dislocation strengthening and solid-solution strengthening were also additional strengthening mechanisms of Cu-Cr composites.