▎ 摘　　要

In this study, Sn-Ag-Cu solder alloys and Sn-Ag-Cu solder alloys reinforced with 0.1 wt% Ag-graphene nanosheets (Ag-GNSs) by mechanical mixing (H for abbreviation) and ball milling (Q for abbreviation), which were referred as SAC, H/0.1Ag-GNSs, and Q/0.1Ag-GNSs, respectively, were used to form solder joints. The creep behavior of the above solder joints was investigated by conducting nanoindentation tests. A method for calculating the strengthening stress generated by the load transfer and orientation of the Ag-graphene nanosheets was proposed. The method considers the geometry and grain data of the Ag-graphene nanosheets, which were obtained through scanning electron microscopy and electron back scattering diffraction. Considering other strengthening stresses generated by the dislocation strengthening, fine grain strengthening, Orowan strengthening for intennetathc compounds and metal matrix nanocomposites, and strengthening stress generated by Ag-graphene nanosheets, a modified constitutive model was proposed to investigate the constitutive behavior for creep performance of solder joints formed by SAC, H/0.1Ag-GNSs and Q/0.1Ag-GNSs. The results show good agreement with the experimental data.