On Precipitation of Tin from Lead-Tin Solid Solution (I). Aging Process in 10%Sn-Pb Alloy

Abstract

The precipitation of tin from super-saturated 10% SnPb solid solution at various temperatures was studied by microscopic observation and microhardness measurement. The aging processes in 10% Sn-Pb alloy are varied acconding to the type of aging. (1) At the aging temperature of higher than about 92°, the lamellar precipitation proceeds slowly from the grain boundary to the grain center. No age-hardening is observed in this case. (2) At the aging temperature of lower than about 45°, the globular aggregation proceeds rapidly from the grain boundary to the grain center at the first stage, and then the mixture of the globular and the lamellar precipitations proceeds from the grain boundary to the grain center at the latter stage. The quenched alloy is age-hardened at the first stage and is softened at the latter stage. (3) At the aging temperature between about 45° and 92°, the mixture of the globular aggregation and the lamellar precipitation proceeds from the grain boundary to the grain center. A little age-hardening is observed in this case.