Influence of Pb impurity on melting point and metallography of Sn‐5wt%Sb alloy

Abstract

Influence of Pb impurity on the melting point and metallography of Sn-5wt%Sb alloy is investigated. The Sn-Sb-Pb three-element alloy made of Pb doped to Sn-Sb systems melts at a temperature lower than the melting point of Sn-5wt%Sb material and exhibits thermal absorption phenomena at 185°C to 190°C and 210°C to 240°C. Also, the three element alloy (1) exhibits a metallography consisting of the crystal grains of Sn-Sb alloy with a small content of Pb and of the grain boundary region mainly made of Pb-Sn alloy, if the Pb doping is low, and (2) the grain boundary region made of Pb-Sn alloy increases as Pb doping is increased. In the temperature rising process, melting starts at the grain boundary region (at about 185°C) and terminates melting at 210°C to 240°C depending on the Pb content. The melting region is gradually expanding from the grain boundary to the interior of the crystal grain. The ternary alloy with Pb concentration adjusted to 1.5 wt% hardly melts at temperatures below 230°C. © 1998 Scripta Technica, Electron Comm Jpn Pt 2, 81(1): 112, 1998