Destruction of silicon nitride whiskers by reaction with metals at high temperatures

Abstract

A preliminary study has been made of the reaction, at elevated temperatures, between whiskers of silicon nitride and pure metals (aluminium and nickel). The subject is important in the context of composite materials using refractory whiskers as a reinforcing component. The method involves reacting the whiskers with a thin, evaporated layer of the metal concerned and observing the results under the electron microscope. The effects of reaction are described and may be explained in terms of either crystallographic etching or recrystallisation of the whisker, though the former appears the more likely. The results do not necessarily reflect the behaviour of bulk composites made from the same constituents.