Oxidation of (Pb, Sn) and (Pb, In) Alloys

Abstract

The oxidation of (Pb,Sn) and (Pb,In) single-phase alloys and the Pb-Sn eutectic was studied using Auger electron spectroscopy (AES) and a scanning Auger microprobe (SAM). The oxidation of the single-phase alloys results in a structure which has been called “an oxide inversion layer”, where the amount of solute in the oxide increases with depth into the oxide layer, reaches a maximum, then decreases to its value in the bulk alloy. The solute content of the oxide is noticeably higher in the region surrounding grain boundaries, due to the enhanced diffusion of the solute. Grain boundary oxidation is also observed in the single-phase alloys. The oxidation kinetics of both the single-phase (Pb,Sn) alloys and the eutectic alloy are logarithmic at 22° C and 90° C, but become parabolic at temperatures greater than 120° C. Pb-3.0 at. percent In alloys follow logarithmic oxidation kinetics up to 150°C and parabolic kinetics between 175°C and 250°C.