Metallographic Etching Reagents: I, for Copper (Classic Reprint)

Lo Zi S Metallographic Etching Reagents for Copper 643 typical of these may be mentioned the work of Stead, of Rosenhain and Haughton, and of Le Chatelier and Bogitch. The descriptions which have been pubhshed on the general subject of metallographic etching consist mainly of compilations of the experience and opinions of workers engaged in metallographic work rather than the result of any systematic study of the subject. A mong these articles may be mentioned that of Hudson of Guertler, and of Czochralski .I nthe third article the subject is treated in the most comprehensive manner, the first two being mainly compilations of current practice in metallographic etching. On account of the dearth of information concerning metallographic etching reagents and methods, a study of the general subject was deemed advisable and was undertaken by this Bureau. The aim is to establish, wherever possible, the principles which underlie the successful methods of etching. It was also anticipated that valuable data might be obtained incidentally relating to the characteristic properties, other than the etching characteristics, of the microstructural constituents of the various alloys used as types. The discussion which follows relates to the results obtained with copper, which was the first type to be considered. Copper was chosen as a starting point in the investigation for two reasons, (i) on account of the technical importance of the metal itself, and (2) because of the fact that it enters into the composition of a large number of commercial alloys. In a general way the etching properties of metallic copper are quite characteristic of the behavior of its single-phase or one-constituent alloys in respect to etching. XL TYPES OF COPPER USED AS SPECIMENS As materials for study specimens of copper representative of five different physical conditions were used. These included c
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