Discovery and implications of hidden atomic-scale structure in a metallic meteorite

TL;DR

This study uncovers a previously hidden FeNi nanophase in a meteorite, revealing complex magnetic behaviors and offering new insights into celestial metallurgy and potential applications in high-energy magnets.

Contribution

It identifies a novel FeNi nanophase in a meteorite, expanding understanding of Fe-Ni phases and their magnetic properties in celestial materials.

Findings

Discovery of a hidden FeNi nanophase in meteorite NWA 6259.

Complex magnetic states arising from ferromagnetic and antiferromagnetic phases.

Implications for celestial metallurgy and development of high-energy magnets.

Abstract

Iron and its alloys have made modern civilisation possible, with metallic meteorites providing one of the human's earliest sources of usable iron as well as providing a window into our solar system's billion-year history. Here highest-resolution tools reveal the existence of a previously hidden FeNi nanophase within the extremely slowly cooled metallic meteorite NWA 6259. This new nanophase exists alongside Ni-poor and Ni-rich nanoprecipitates within a matrix of tetrataenite, the uniaxial, chemically ordered form of FeNi. The ferromagnetic nature of the nanoprecipitates combined with the antiferromagnetic character of the FeNi nanophases give rise to a complex magnetic state that evolves dramatically with temperature. These observations extend and possibly alter our understanding of celestial metallurgy, provide new knowledge concerning the archetypal Fe-Ni phase diagram and supply new information for the development of new types of sustainable, technologically critical high-energy magnets.