Thermal and microstructural analysis of the low-melting Bi-In-Pb alloy

Low-melting alloys, based on bismuth and indium, have found commercial use in soldering, safety devices, coatings, and bonding applications. In this respect, the accurate knowledge of their thermal properties such as melting and solidification temperatures, latent heat of melting, supercooling tendency, etc. is of large importance. In the present research, low-melting alloy with nominal composition Bi40In40Pb20 (at. %) was investigated by means of scanning electron microscopy (SEM) with energy dispersive Xray spectrometry (EDS) and by differential scanning calorimetry (DSC). Microstructural and chemical (SEM-EDS) analysis has revealed the existence of two coexisting phases in the prepared alloy, which was identified as BiIn and (Pb). Melting and solidification temperatures and the related heat effects were measured by the DSC technique. The solidus temperature obtained from the DSC heating curves was 76.3 °C and the solidus temperature obtained from the corresponding DSC cooling runs was 61.2 °C. The experimentally obtained results were compared with the results of thermodynamic calculation according to CALPHAD (calculation of phase diagram) approach, and a close agreement was noticed.