The microstructure of lead-base alloys

Abstract

An extensive literature search has not revealed any comprehensive publication dealing mainly with the optical metallography of lead-base alloys. During the past four years, Gould-National has conducted systematic studies on pure lead and on seven binary and four ternary systems at various concentrations. The systems are: SbPb, CaPb, LiPb, CdPb, AgPb, AsPb, SnPb, AsSbPb, AgSbPb, CdSbPb, and SnSbPb. Over two thousand lead alloy specimens have been examined metallographically. The objective of our study was to develop lead-base alloys having superior physical and electrochemical corrosion resistance properties. The paper presents observed metallographic structures of the various binary and ternary lead alloys, cast under air or inert atmosphere and with controlled solidification rates. The metallographic structures have been used to reveal the multicrystalline aggregation of phase or phases, to evaluate the grain size and grain growth, to detect grain boundary precipitation during age hardening, to detect microporosity and cracks in cast alloys, and to examine the nature of the corrosion attack mechanism on alloys subjected to anodic corrosion. A detailed description of metallographic sample preparation techniques used on various lead alloys is presented.