EBSD Study of Fe-Ni phases on a L4-L5 ordinary chondrite meteorite

Abstract

The research on interplanetary materials such as comets, meteors or meteorites contributes to understand the origin and evolution of our Solar System. They provide highly valuable information on the relation between the conditions of formation and their microstructure, chemical composition and magnetic properties. Orientation relationships of the Fe-Ni system and distribution of body-centered cubic kamacite-α, face-centered cubic taenite-γ and an eutectic solidification of both, as plessite, is the focus of this study. Because Fe-Ni phases are abundant in meteorites and are magnetic, this investigation has also particular interest on paleomagnetism, especially in terms of long-term stability of remanent magnetization. Formation of plessite is dependent on the Ni content of the alloy and the reaction conditions found at eutectic solidification, facilitating texture development with low energy contact interfaces. Different reaction paths can develop several forms of plessite, leading to different types of microstructure, allowing us to figure out the meteorite's formation conditions in space. This work presents a preliminary study of a meteorite, recovered from Morocco and suspected to be related with HAMLET’s meteorite, mostly by Electron Backscattered Diffraction (EBSD) of the Scanning Electron Microscope (SEM). This technique shows flexibility for materials characterization, predominantly in metals due to their polished conductive surface. Also, petrographic analysis, microstructure investigation by SEM and chemical composition by Energy Dispersive Spectroscopy (SEM/EDS) and X-Ray Diffraction (XRD) were exploited to complete the conclusions.