Characterization of bismuth-tin-lead and bismuth-tin-lead-cadmium fusible alloys

Microstructure, electrical, mechanical and thermal properties of quenched bismuth-tin eutectic, Rose (Bi50Sn22.9Pb27.1) and Woods (Bi50Sn12.5Pb25Cd (12.5)) alloys have been investigated using scanning electron microscopy, X-ray diffraction analysis, the double bridge method, the dynamic resonance method, Vickers hardness measurement and thermal analysis. Woods alloy (Bi-Pb-Sn-Cd) has low electrical resistivity and melting point but a high elastic modulus and internal friction when compared with the Rose (Bi-Pb-Sn) alloy. The presence of cadmium in Woods alloy decreases its melting point and electrical resistivity with an increase in its elastic modulus, which improves the mechanical properties. Woods alloy (Bi-Pb-Sn-Cd) has better properties, which make it useful in various applications such as in protection shields for radiotherapy, locking of mechanical devices and welding at low temperature.