Color Metallography

Abstract

Precipitation reactions are of great importance in engineering alloys. This general phenomenon occurs in many different alloy systems when one phase transforms into a mixed-phase system as a result of cooling from high temperatures. The solid-state reaction results in a phase mixture of matrix phase and precipitates that nucleate and coarsen. The matrix may share a similar crystal structure to the parent phase, but has a different composition and often a dissimilar lattice parameter, while the precipitated phase may differ in crystal structure, composition, lattice parameter, and degree of long-range order. The resultant properties of the alloy after precipitation are a direct result of the type, size, shape, and distribution of the precipitated phase. Two figures showing 6061.