Effect of rare earth Ce on the thermal behavior, microstructure and mechanical properties of Zn-30Sn-2Cu high temperature lead-free solder alloy

The aim of the present study is to investigate the thermal behavior, microstructure and mechanical properties of high temperature Zn-30Sn-2Cu-xCe (x = 0, 0.05, 0.1, 0.5 wt%) Pb-free solders. The alloying of Ce refined the microstructure and increased the melting point of the solders. Zn-30Sn-2Cu-0.05Ce sample showed the best elongation, while the best ultimate tensile strength (UTS) and yield strength (YS) appeared in Zn-30Sn-2Cu-0.1Ce sample. The UTS of the alloys ranged from 44.02 to 64.95 MPa and the YS ranged from 32.73 to 51.83 MPa. Besides, the microhardness enhanced slightly with the addition of Ce. The analysis of the fractographies showed that the fracture mode turned from mixed brittle fracture into mixed ductile fracture with the addition of Ce.