Enhancement of load transfer by interfacial bonding in Al-Cu-Mg joints under the in-situ synergistic effect of carbon nanotubes and silicon nitride

Abstract

In this paper, carbon nanotubes (CNTs) and silicon nitride (Si3N4) were innovatively introduced to in-situ form composite Al-Cu-Mg joints by laser welding. Morphology and composition results indicated that CNTs were either dispersedly arranged in the fusion zone or tightly coupled with nano-scale Si3N4 and Mg2Si precipitates. Crystallographically, coherent interfaces were built between CNTs and surroundings. Besides, geometric phase analysis (GPA) of Al(111)//Al4C3(10−12) interface indicated that the microstrain transfer and transformation between the Al-Cu-Mg matrix and the CNTs was mainly attributed to the formation of Al4C3. Tensile strength and elongation rate of the joint with composite additives were increased by 30.4% and 162%, respectively, compared with single laser welding. This work provided a new idea for optimizing the bonding design of the interface between CNTs and aluminum matrix to improve the load transfer efficiency.