A New Nitride Precipitate in Iron-Silicon Alloys

Abstract

RECENT work has indicated the presence of a new nitride precipitate in iron-silicon alloys. Leak, Thomas and Leak¹ using internal friction methods investigated nitrided iron-silicon alloys and deduced the presence of an unknown precipitate thought to be an iron-silicon nitride. Turkdogan, Bills and Tippet², using X-ray diffraction methods, examined nitrided iron-silicon alloys and found precipitates with an unknown structure which varied with the composition and heat-treatment of the specimen. After the precipitates had been isolated from the alloys by the Beeghly³ bulk-extraction method, they were found to be α-Si₃N₄ silicon nitride. It was suggested² that the precipitates formed in the metal specimens were a complex nitride that decomposed during isolation. With the advent of the extraction replica method, in which included material can be isolated from metal specimens after very mild chemical treatments compared with bulk-extraction methods, a further attempt has now been made to isolate the new precipitate.