Solid solubility in isolated nanometer-sized alloy particles in the Sn-Pb system

Abstract

The finite size effect on both the solid solubility and the thermal expansion coefficient in nanometer-sized lead particles was examined by in-situ transmission electron microscopy. The solid solubility of tin in approximately 12-nm-sized particles of lead at room temperature was evaluated be higher than 30 atomic percent, which is almost ten times higher than that in the corresponding bulk lead. The thermal expansion coefficient of lead increased from 29×10-6 K-1 for bulk to 38×10-6 K-1 when the size of particles decreased from ∞ (bulk) to 16 nanometers. The increment of the thermal expansion coefficient with decreasing size of particles suggests the reduction of the cohesive energy and therefore the reduction of the elastic modulus with decreasing size of particles. It is then considered that the suppression of the strain energy in the solid solution may be responsible for the enhanced solid solubility in nanometer-sized alloy particles.