Electrolytic Extractions of Precipitates From Steel Alloys

Abstract

During aging of an iron based alloy, the degree of preparation has significant effects on the properties of the alloy. Long-term heat treatments can produce rather large precipitates. In order to obtain compositional and/or structural information from these large precipitates, it is often necessary to examine them in the absence of the surrounding matrix. However it has been found that the extraction replica technique is reliable only for particles 1 μn in size or less. Any larger particle tends to stay embedded in the matrix. We have found electrolytic extraction from the this bulk to be the only reliable way to obtain precipitate particles larger than 1 um. By modifying a gravimetric-vacuum filter assembly, a new method of extraction has been developed, eliminating the time consuming and laborious steps of centrifuging the electrolyte, retrieval of precipitates from test tubes, vacuum drying, and acid cleaning of glassware.