Homogeneous dispersion of graphene and interface metallurgical bonding in Sn-Ag-Cu alloy induced by ball milling

The addition of graphene is expected to improve the properties of solder and graphene reinforced Sn-Ag-Cu (GNSs/SAC) is considered to be able to adapt to harsh service environment. However, it is difficult to realize homogeneous dispersion of reinforcement and the metallurgical bonding between graphene and Sn-Ag-Cu alloys. In this study, composite solders with various dispersion of graphene have been prepared by different ball milling method. The microstructure characterization shows that incoherent interface and amorphous interface have been produced between graphene and Sn. The results of Energy Dispersive Spectrometer (EDS) and X-ray diffraction (XRD) indicate that the interstitial solid solution of carbon atoms in beta-Sn is the cause of metallurgical bonding. The relative amount of the two types of interfaces and the dispersion of graphene were evaluated. The incoherent interface of composites tends to form at lower milling speed, and its thermal expansion response indicates that the interface has more effective load transfer, while the amorphous interface is opposite. Besides, the {101} fiber texture was also confirmed to be formed during ball milling and sintering. Finally, the nano indentation test verified the metallurgical bond, and the mechanical properties of the GNSs/SAC composites are determined by the interface type and graphene dispersion.

Automated summary

The addition of graphene is expected to improve the properties of solder and graphene reinforced Sn-Ag-Cu (GNSs/SAC) can adapt to harsh service environments. Different ball milling methods were used to prepare composite solders with varying graphene dispersion. The study found that carbon atoms in beta-Sn form an interstitial solid solution, leading to metallurgical bonding between graphene and Sn-Ag-Cu alloys, with the interface type and graphene dispersion affecting the mechanical properties of the composites.