Study on Microstructure and Properties of Sn-43.5Bi-27Pb Low Melting Point Alloy

JMatPro software was used to calculate the phase composition of Sn-Bi-Pb ternary low melting point alloys with different compositions. The microstructure, melting properties and mechanical properties of Sn-43.5Bi-27Pb alloy were studied by scanning electron microscopy（SEM）, differential thermal analysis（DTA） and X-ray diffraction（XRD）. The results show that the Sn-43.5Bi-27Pb alloy contains three phases: Sn phase, Bi phase and Pb₇Bi₃intermediate phase, the melting point is 96.5 ℃. The tensile strength of the alloy is 55 MPa, which is slightly lower than that of Sn-58Bi eutectic alloy, and the elongation after fracture is higher than the elongation of 14.9% of Sn-58Bi, which is 52.1%. The microhardness of the alloy is 13.1 HV, which is lower than the hardness of 20.7 HV of Sn-58Bi eutectic alloy.