Wetting transition of grain boundaries in tin-rich indium-based alloys and its influence on electrical properties

Abstract

The microstructural evolution of tin-rich indium-based alloys after the grain boundary wetting phase transition in the (liquid + γ) twophase region of the tin-indium phase diagram and its influence on the electrical conductivity were investigated. Five tin-indium alloys, Sn75In 25, Sn70In30, Sn65In35, Sn60In40, and Sn55In45, were annealed between 393 and 454 K for 24 h. The melted area of the grain boundary triple junctions and grain boundaries increased with increasing the annealing temperature. The microstructures of as-prepared specimens of Sn 75In25 and Sn70In30 alloys had different amounts of completely wetted grain boundaries after annealing. The XRD results show the changes in phases that underwent the eutectic transformation during quenching from various annealing temperatures. The electrical conductivity of annealed tinindium specimens with various microstructures was measured. It increased with both annealing temperature and tin content. © 2010 The Japan Institute of Metals.