A MICROTEXTURE STUDY OF EUTECTIC CARBIDES IN WHITE CAST IRONS USING ELECTRON BACKSCATTER DIFFRACTION

White cast irons have a microstructure composed of a ferrous matrix wi th hexagonal and/or orthorhombic carbides, M7C, and M3C, respectively. The US Bureau of Mines has implemented a study programme to improve m icrostructure and thereby wear resistance of these alloys. This work i ncluded electron back-scatter diffraction in a scanning electron micro scope to identify the hexagonal and orthorhombic phases from their cry stallography and subsequently establish their microtextures. Crystal s tructures of these carbides were identified and their microtextures we re obtained from specific spatial locations within micrometre resoluti on. Such resolution allowed the identification of thin shells of M3C ( 1-5 mum thick) to be distinguished from cores of M7C3 (10-20 mum thick ). Microtexture results showed that M7C3 carbides without M3C shells g rew predominantly in the [0001] direction, whereas those with M3C shel ls were much less textured with the M3C shell phase having a random mi crotexture.