Effects of rare earth la on the microstructure and melting property of (Ag-Cu₂₈)-30Sn alloys prepared by mechanical alloying

To obtain novel intermediate temperature alloy solders with a melting temperature of 400-600°C, nominal (Ag-Cu₂₈)-30Sn alloys without or with a trace addition (0.5 or 1.0 wt.%) of rare earth (RE) element La were prepared by mechanical alloying. The aim of this research is to investigate the effects of the addition of La on the microstructures, alloying process and melting properties of (Ag-Cu₂₈)-30Sn alloys. The results show that the addition of La produces no new phase. A trace amount of La addition can effectively refine the grain size, but the excessive addition of 1.0 wt.% La inhibits the alloying process. The influence of La on the melting temperatures of solder alloys is negligible. However, the trace addition of 0.5 wt.% La can distinctly reduce the fusion zone and improve the melting property of (Ag-Cu₂₈)-30Sn alloys.