On the Nature of Dislocation Etch Pits in Tungsten

Abstract

Some details on dislocation etch pits in tungsten are presented. Etch pits are produced electrolytically with 2% NaOH solution and the Millner‐Sass reagent, and chemically with a potassium ferricyanide etchant. All three etchants can reveal dislocations, but only on certain crystallographic planes. In addition to etch pits, pyramids are produced on octahedral, or nearly octahedral planes. These pyramids do not seem to be related to dislocations. There is no guarantee that all pits correspond to dislocations since impurities, such as carbon, markedly affect the size, shape, and density of etch pits. It was observed that the density of etch pits depends also on the current density during electrolytic etching.